# ISRO Interview Questions with Answers

6 previously-asked interview questions from ISRO's hiring process, each with the correct answer and a worked explanation. Written against the company's actual test pattern.

_Source: Astra (https://useastra.in). Updated 2026-09-05._

### 1. What is the difference between a microprocessor and a microcontroller?

**Answer:** A microprocessor is a CPU needing external memory and peripherals, used in general purpose computers. A microcontroller integrates CPU, memory, and IO peripherals on one chip and is used in embedded and control systems.

**Explanation:** Microprocessor needs external parts; microcontroller is all in one.

### 2. What is modulation and why is it used?

**Answer:** Modulation varies a property (amplitude, frequency, or phase) of a high frequency carrier signal according to a message signal. It is used to transmit signals efficiently over long distances, allow smaller antennas, and let multiple signals share a medium.

**Explanation:** Impressing a message on a carrier for efficient transmission.

### 3. What is the difference between AM and FM?

**Answer:** Amplitude Modulation varies the carrier amplitude with the message and is simpler but more noise prone. Frequency Modulation varies the carrier frequency, giving better noise immunity and audio quality at the cost of more bandwidth.

**Explanation:** AM varies amplitude; FM varies frequency and resists noise better.

### 4. How does a satellite stay in orbit?

**Answer:** A satellite stays in orbit because its forward velocity balances the gravitational pull of the Earth, so it continually falls toward the Earth while moving forward fast enough to keep missing it. The required speed depends on the orbital altitude.

**Explanation:** Orbital velocity balances gravity, so it keeps falling around Earth.

### 5. Tell me about yourself.

**Answer:** Give a concise 60 to 90 second overview: your branch and degree, core technical strengths, a relevant project, and why ISRO interests you. Emphasise depth in your branch fundamentals.

**Explanation:** Structured pitch: background, strengths, project, fit.

### 6. Why do you want to join ISRO?

**Answer:** Mention ISRO world-class space missions, the chance to work on cutting-edge technology for national and scientific benefit, the prestige and learning, and contributing to India space program. Tie it to your branch and passion.

**Explanation:** World-class space missions; national and scientific impact.

More ISRO preparation, including the full recruitment process: https://useastra.in/campus/isro