100+ R&D Engineer Interview Questions and Answers

Answering questions related to ideal characteristics of opamp, CMRR, input impedance, impedance matching, MPTT, and significance of opamp in D-A and A-D convertors.

• Ideal characteristics of opamp include high gain, high input impedance, low output impedance, and low noise.

• CMRR stands for Common Mode Rejection Ratio and it measures the ability of an opamp to reject common mode signals.

• The practical significance of CMRR is that it helps in reducing noise and interference in the ...read more

I would start by identifying the root cause of the crash and then work on finding a solution to fix it.

• First, I would analyze the crash dump to identify the error message or code that caused the crash.

• Then, I would review the software code to understand the context of the error and identify any potential bugs or issues.

• I would also check for any known issues or bugs that have been reported by other customers.

• Once I have identified the root cause of the crash, I would work on ...read more

Explanation of full wave bridge rectifier, transformer losses, filter usage, and Zener diode as regulator.

• Full wave bridge rectifier converts AC to DC using four diodes arranged in a bridge configuration

• Transformer losses occur due to core saturation and resistance in the windings

• Filters are used to smooth out the DC output and reduce ripple

• Zener diode operates in reverse breakdown region and maintains a constant voltage output

• Zener diode can be used as a voltage regulator in...read more

Comparison of 8086 with present processors and why PC processors can't be used in mobiles

• 8086 had a 16-bit data bus and 20-bit address bus, while modern processors have 64-bit data bus and 48-bit address bus

• 8086 had a clock speed of 5-10 MHz, while modern processors have clock speeds in GHz

• Mobile processors are designed to be power-efficient and have lower clock speeds compared to PC processors

• Mobile devices use different storage technologies like eMMC, UFS, and NVMe SSDs

• Mobi...read more

Question on breadth first search, longest common subsequence, and output of code written on paper.

• Breadth first search is a graph traversal algorithm that visits all the vertices of a graph in breadth-first order.

• Longest common subsequence is the longest subsequence common to all sequences in a set of sequences.

• Output of code written on paper refers to writing code on paper and then analyzing the output without actually running the code.

Dynamic memory allocation in C and C++ can be done using malloc, calloc, realloc and new operators.

• malloc() function is used to allocate a block of memory of specified size.

• calloc() function is used to allocate a block of memory and initializes it to zero.

• realloc() function is used to resize the previously allocated memory block.

• new operator is used in C++ to allocate memory for an object.

• Memory allocated using these functions should be freed using free() function in C and de...read more

You can turn on one switch for a few minutes, turn it off and turn on another switch. The remaining switch will be for the third bulb.

• Turn on switch 1 and leave it on for a few minutes

• Turn off switch 1 and turn on switch 2

• Leave switch 2 on for a few minutes

• Turn off switch 2 and turn on switch 3

• The bulb that is off and warm to the touch is connected to switch 1

• The bulb that is on is connected to switch 2

• The bulb that is off and cold to the touch is connected to switch 3

The point where maximum intersections are happening in a 2D graph can be found by analyzing the overlapping regions of lines or curves.

• Identify all the lines or curves in the graph

• Determine the regions where these lines or curves overlap

• Count the number of intersections in each overlapping region

• Find the point with the highest number of intersections

Abstract classes are used when we want to provide a default implementation, while interfaces are used when we want to enforce a contract.

• Use abstract classes when you want to provide a default implementation for some methods.

• Use interfaces when you want to enforce a contract that must be implemented by the implementing class.

• Abstract classes can have constructors, while interfaces cannot.

• A class can implement multiple interfaces, but can only inherit from one abstract class.

• A...read more

I approach conflicts by actively listening, identifying the root cause, and finding a mutually beneficial solution.

• Listen to all parties involved and understand their perspectives

• Identify the root cause of the conflict

• Brainstorm potential solutions with all parties involved

• Find a mutually beneficial solution that addresses the root cause

• Communicate the solution clearly and ensure all parties are satisfied

Types of voltage regulators include linear regulators, switching regulators, and shunt regulators.

• Linear regulators: provide a stable output voltage by dissipating excess power as heat (e.g. LM317)

• Switching regulators: more efficient than linear regulators by switching the input voltage on and off (e.g. LM2596)

• Shunt regulators: regulate voltage by shunting excess current to ground (e.g. TL431)

To handle huge amount of data efficiently, consider using distributed storage systems, data compression techniques, and data partitioning.

• Utilize distributed storage systems like Hadoop or Spark to store and process large volumes of data across multiple nodes

• Implement data compression techniques such as gzip or snappy to reduce storage space and improve data transfer speeds

• Partition data into smaller chunks based on key attributes to distribute workload and improve query perf...read more

Rotate array clockwise K times, implement binary search

• Rotate the array by reversing the array and then reversing the first K elements and then reversing the remaining elements

• Implement binary search by dividing the array into two halves and comparing the middle element with the target

• Repeat the binary search until the target is found or the array is exhausted

Pointers are variables that store memory addresses. A dangling pointer is a pointer that points to a memory location that has been deallocated.

• Pointers are used to access memory directly

• They can be used to pass values by reference

• Dangling pointers can cause program crashes or unexpected behavior

Find max of multiple of 3 elements in an array with positive and negative values.

• Iterate through the array and keep track of the three largest positive and negative numbers.

• Multiply the three largest positive numbers and the three largest negative numbers by each other and find the maximum of the resulting products.

Cake can be cut into 8 equal pieces by making 3 cuts.

• Make two cuts to divide the cake into quarters, then make a third cut through all quarters to get 8 equal pieces.

• Each cut should be made perpendicular to the previous cut.

• The size of the cake does not matter as long as it is a cylindrical or rectangular shape.

OSI model is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system.

• OSI model has 7 layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

• Each layer has a specific function and communicates with the layers above and below it.

• Linked list is a data structure that consists of nodes linked together in a sequence.

• Each node contains data and a pointer to the next node in the lis...read more

Program to fetch second highest number from array

• Sort the array in descending order

• Return the second element of the sorted array

To find if there is a cycle in a linked list, left view of a tree, Comparator vs Comparable in Java, and internal implementation of Hashmap.

• To find a cycle in a linked list, you can use Floyd's Tortoise and Hare algorithm.

• To get the left view of a tree, you can perform a level order traversal and print the first node at each level.

• Comparator in Java is used to compare objects based on custom criteria, while Comparable is an interface used to define natural ordering of objects...read more

The working principle of the project developed earlier involved utilizing machine learning algorithms to analyze data and make predictions.

• Used supervised learning techniques to train the model

• Implemented feature engineering to improve model performance

• Utilized cross-validation to assess model accuracy

• Applied the trained model to new data for prediction

I have experience working with various softwares including Fusion 360 and am comfortable using it.

• I have worked with AutoCAD, SolidWorks, and Fusion 360 in previous projects

• I am proficient in creating 3D models, simulations, and prototypes using Fusion 360

• I have used Fusion 360 for designing mechanical components and assemblies

An inverter is a device that converts DC power to AC power and vice versa in backup mode.

• Inverter converts DC power from a battery into AC power for household appliances.

• During backup mode, inverter converts AC power from grid into DC power to charge the battery.

• Common types of inverters include sine wave, modified sine wave, and square wave inverters.

Inheritance is a mechanism in object-oriented programming where a new class is created from an existing class.

• It allows the new class to inherit the properties and methods of the existing class.

• There are different types of inheritance such as single, multiple, multilevel, and hierarchical.

• Single inheritance involves a child class inheriting from a single parent class.

• Multiple inheritance involves a child class inheriting from multiple parent classes.

• Multilevel inheritance inv...read more

When an OSPF broadcast domain is broken into 2 and then back to 1, the DR and BDR election process will be triggered again.

• When the broadcast domain is split, each segment will have its own DR and BDR elected based on priority and router ID.

• When the broadcast domain is merged back into one, a new DR and BDR election will take place among all routers in the domain.

• The election process considers the priority value set on each router, with higher priority routers having a better...read more

Some competitors of Schneider Electric include Siemens, ABB, and Eaton.

• Siemens

• ABB

• Eaton

The question is about capacitor charging time when battery connected and swapping program without using variable in any embedded program structure.

• Capacitor charging time can be calculated using the formula t = RC where R is the resistance and C is the capacitance.

• Swapping program without using variable can be achieved by using pointers to swap the values of two variables.

• Embedded program structure typically includes initialization, main loop, and interrupt service routines.

• M...read more

Segmentation is the process of dividing a larger entity into smaller parts or segments.

• It is commonly used in image processing to separate objects from the background.

• Segmentation can also refer to dividing a market into smaller groups based on demographics or behavior.

• In computer science, segmentation refers to dividing memory into smaller parts for more efficient use.

• Segmentation can also be used in biology to divide cells or tissues into smaller parts for analysis.

Water-based coating development involves several stages including formulation, testing, optimization, and scale-up.

• Formulation of the coating composition with water as the primary solvent

• Testing the coating for properties such as adhesion, durability, and appearance

• Optimizing the formulation based on test results and customer requirements

• Scaling up the production process for commercial use

The change over time in an inverter refers to the time it takes for the inverter to switch from one power source to another.

• Change over time is typically measured in milliseconds.

• It is important for inverters to have a fast change over time to ensure seamless power supply.

• Factors affecting change over time include the type of inverter and the complexity of the power source.

• For example, a high-quality inverter designed for critical applications may have a faster change over ti...read more

PCM material is phase change material used for storing and releasing thermal energy. Refrigeration is the process of cooling a space or substance. System design involves determining components and layout for efficient operation.

• PCM material is used for storing and releasing thermal energy through phase change processes.

• Refrigeration is the process of removing heat from a space or substance to lower its temperature.

• System design involves selecting components like compressors, ...read more

Outliers are data points that significantly differ from other data points. Outlier detection algorithms identify and remove these anomalies.

• Outliers are data points that fall far outside the normal range of values in a dataset.

• Outlier detection algorithms include statistical methods like Z-score, Tukey's fences, and machine learning techniques like isolation forests and one-class SVM.

• Outliers can skew statistical analysis and machine learning models, so it is important to det...read more

Operations on lathe machines include turning, facing, drilling, boring, knurling, and threading.

• Turning: Rotating the workpiece to create cylindrical shapes

• Facing: Creating a flat surface at the end of the workpiece

• Drilling: Making holes in the workpiece

• Boring: Enlarging existing holes in the workpiece

• Knurling: Adding a textured pattern to the workpiece for better grip

• Threading: Cutting threads on the workpiece for screws or bolts

Specification sheet provides detailed information about a product's features and specifications, while data sheet provides technical data and performance characteristics.

• Specification sheet includes details like dimensions, materials, and features of a product.

• Data sheet provides technical data such as performance characteristics, electrical specifications, and operating conditions.

• Both sheets are essential for understanding and evaluating a product before making a purchase d...read more

Counters are digital circuits that count the number of clock cycles or events that occur within a system.

• Synchronous counters use a common clock signal to synchronize the counting process.

• Asynchronous counters use individual clock signals for each flip-flop, allowing for more flexibility in counting sequences.

• Synchronous counters are faster and more reliable, but require a stable clock signal.

• Asynchronous counters are slower and less reliable, but can be used in situations wh...read more

RTOS is designed for real-time applications with predictable response time, while normal OS is designed for general-purpose computing.

• RTOS provides deterministic scheduling and prioritization of tasks.

• Normal OS may have non-deterministic scheduling and may not prioritize tasks.

• RTOS has low latency and high throughput.

• Normal OS may have higher latency and lower throughput.

• RTOS is used in embedded systems, automotive systems, and aerospace systems.

• Normal OS is used in desktops,...read more

A prime number checking program in C language

• Take input from user

• Loop through 2 to n/2 and check if n is divisible by any number

• If not divisible, then it is a prime number

• Print the result

Singleton design pattern ensures only one instance of a class is created and provides a global point of access to it.

• Create a private constructor to prevent direct instantiation of the class

• Create a private static instance of the class

• Create a public static method to access the instance

• Ensure thread safety by using synchronized keyword or static initialization block

• Example: Database connection manager

Find the first non-repeating character in a string.

• Iterate through the string and count the frequency of each character.

• Iterate through the string again and return the first character with frequency 1.

• Use a hash table to store the frequency of each character.

To configure a GPS, one needs to set up the device and choose a protocol to communicate with it.

• Connect the GPS device to a computer or mobile device

• Choose a protocol such as NMEA or UBX

• Configure the baud rate and data format

• Set up the device to receive signals from enough satellites

• Test the GPS to ensure it is working properly

Array list and hashmap are data structures used for storing and accessing data in memory.

• Array list is a dynamic array that can grow or shrink in size as needed.

• Hashmap is a key-value pair data structure that allows for fast retrieval of values based on their keys.

• Array list is implemented using an array, while hashmap is implemented using a hash table.

• Array list is useful when the data needs to be accessed sequentially, while hashmap is useful when the data needs to be acces...read more

Different types of networking devices include routers, switches, hubs, modems, access points, and firewalls.

• Routers: Used to connect multiple networks together and route data between them.

• Switches: Used to connect devices within a network and manage traffic efficiently.

• Hubs: Used to connect multiple devices in a network, but they operate at a lower level than switches.

• Modems: Used to modulate and demodulate digital data for transmission over analog communication lines.

• Access ...read more

The major heating components in an EV motor are the stator winding and the rotor.

• Stator winding: The stator winding is responsible for generating a rotating magnetic field in the motor. It can experience heating due to electrical resistance.

• Rotor: The rotor is the rotating part of the motor and can also generate heat due to friction and electrical resistance.

• Cooling system: EV motors often have a cooling system to dissipate heat generated by the stator winding and rotor.

• Therm...read more

The amount of current that a 1mm2 wire can carry depends on various factors.

• The current carrying capacity of a wire depends on its material, temperature, and insulation.

• Copper wires typically have a higher current carrying capacity compared to aluminum wires.

• The current rating of a wire is usually specified by its manufacturer.

• The current carrying capacity can be affected by factors such as wire length and ambient temperature.

• For example, a 1mm2 copper wire with PVC insulatio...read more

GPS uses satellites to determine the location of a device or object.

• GPS receivers use signals from at least 4 satellites to triangulate the device's location

• The GPS system is maintained by the US government and is free to use

• GPS can be used for navigation, tracking, and geotagging

• GPS accuracy can be affected by factors such as weather and obstructions

• GPS can also be used in conjunction with other technologies such as cellular networks and Wi-Fi for improved accuracy

MVC filters are used to intercept and modify HTTP requests and responses in ASP.NET MVC applications.

• Filters can be used for authentication, caching, logging, and exception handling.

• Filters can be applied globally or to specific controllers or actions.

• The execution sequence of filters is determined by their type and scope.

• The order of execution can be modified using the Order property.

• Some common filter types include Authorization filters, Action filters, Result filters, and ...read more

Organisation can be managed by setting clear goals, effective communication, delegation of tasks, and fostering a positive work culture.

• Set clear goals and objectives for the team to work towards.

• Communicate effectively with team members to ensure everyone is on the same page.

• Delegate tasks based on individual strengths and skills.

• Foster a positive work culture by promoting teamwork, recognition, and open communication.

• Regularly review and adjust strategies to ensure the orga...read more

Adding new flavour involves creating unique and appealing taste profiles to enhance product offerings.

• Experimenting with different ingredients and combinations to create a distinct flavour profile

• Conducting sensory evaluations to gather feedback on taste preferences

• Considering market trends and consumer preferences when developing new flavours

• Collaborating with food scientists and flavor chemists to optimize flavour profiles

• Examples: introducing a spicy twist to a traditional...read more