Question 1

What is the SI unit of electric current?

Accepted Answer

The SI unit of electric current is the Ampere (A), named after French physicist André-Marie Ampère. It is one of the seven base SI units and measures the flow of electric charge per unit time.

Question 2

Which of the following phenomena occurs when light bends while passing from one medium to another?

Accepted Answer

Refraction is the bending of light when it passes from one medium to another with a different optical density. This occurs because light travels at different speeds in different media, causing the light ray to change direction at the boundary.

Question 3

Which scientist formulated the law of universal gravitation?

Accepted Answer

Sir Isaac Newton formulated the law of universal gravitation in the late 17th century. This law states that every particle in the universe attracts every other particle with a force proportional to the product of their masses and inversely proportional to the square of the distance between them (F = G m₁m₂/r²).

Question 4

What is the SI unit of force?

Accepted Answer

The Newton (N) is the SI unit of force, named after Sir Isaac Newton. One Newton is defined as the force required to accelerate a mass of one kilogram at a rate of one meter per second squared (F = ma).

Question 5

Which physical quantity is measured in Hertz (Hz)?

Accepted Answer

Hertz (Hz) is the SI unit of frequency, representing the number of cycles or oscillations per second. It is named after German physicist Heinrich Hertz.

Question 6

What is the SI unit of temperature?

Accepted Answer

The Kelvin (K) is the SI unit of temperature. It is an absolute temperature scale where 0 K represents absolute zero (the lowest possible temperature). The Celsius scale is commonly used but is not the SI unit.

Question 7

Which of the following is the SI unit of electric current?

Accepted Answer

The SI unit of electric current is the Ampere (A), named after French physicist André-Marie Ampère. It is defined as the flow of one coulomb of charge per second through a conductor.

Question 8

Which physical quantity is measured by the unit 'Pascal'?

Accepted Answer

Pascal (Pa) is the SI unit of pressure. It is defined as one newton per square metre (N/m²). It is named after French mathematician and physicist Blaise Pascal. Pressure = Force / Area.

Question 9

What is the SI unit of pressure?

Accepted Answer

The Pascal (Pa) is the SI unit of pressure, named after French mathematician and physicist Blaise Pascal. One Pascal is defined as one Newton of force applied over an area of one square metre (1 Pa = 1 N/m²).

Question 10

A person standing on the ground observes that the angle of elevation to the top of a building is 30°. If the person moves 10 meters closer to the building, the angle of elevation becomes 45°. What is the approximate height of the building?

Accepted Answer

This question tests the application of trigonometry and angles of elevation in everyday physics scenarios. Using tan(30°) = h/(d+10) and tan(45°) = h/d, where h is height and d is initial distance, we can solve: tan(30°) = 1/√3 ≈ 0.577 and tan(45°) = 1. From tan(45°) = h/d, we get h = d. Substituting into the first equation: 1/√3 = d/(d+10), which gives d(√3) = d + 10, so d(√3 - 1) = 10, therefore d ≈ 13.66 m. Thus h ≈ 13.66 m or approximately 13.7 meters.

Question 11

Which physicist formulated the law of universal gravitation?

Accepted Answer

Sir Isaac Newton formulated the law of universal gravitation in 1687, published in his work 'Philosophiæ Naturalis Principia Mathematica' (Mathematical Principles of Natural Philosophy). This law states that every mass attracts every other mass with a force proportional to the product of their masses and inversely proportional to the square of the distance between them.

Question 12

Which of the following is an example of a non-contact force?

Accepted Answer

Gravitational force is a non-contact force that acts between objects without physical contact. Other examples include magnetic force and electrostatic force. These forces operate through fields (gravitational field, magnetic field, electric field).

Question 13

At what temperature do Celsius and Fahrenheit scales show the same numerical value?

Accepted Answer

The Celsius and Fahrenheit scales show the same numerical value at –40°. This can be derived from the conversion formula: °F = (°C × 9/5) + 32. Setting °F = °C and solving gives –40.

Question 14

What is the speed of light in vacuum according to the SI system?

Accepted Answer

The speed of light in vacuum is defined as exactly 299,792,458 meters per second (m/s), commonly approximated as 3 × 10⁸ m/s or 3 lakh km/s. This is a fundamental constant in physics, denoted by the symbol 'c'.

Question 15

In physics, the SI unit of pressure is the Pascal (Pa). One Pascal is equivalent to which of the following?

Accepted Answer

1 Pascal = 1 Newton per square meter (N/m²). This is the fundamental definition of pressure in the SI system.

Question 16

A person standing on the surface of Earth experiences a gravitational acceleration of approximately 9.8 m/s². If this same person were standing on the surface of Jupiter (assuming they could survive), where the gravitational acceleration is about 24.79 m/s², how would their weight change compared to Earth?

Accepted Answer

Weight is directly proportional to gravitational acceleration (W = mg). On Jupiter, g ≈ 24.79 m/s², which is approximately 2.53 times Earth's gravitational acceleration of 9.8 m/s². Therefore, a person's weight on Jupiter would be approximately 2.53 times their weight on Earth. For example, a 100 kg person on Earth would weigh about 253 kg on Jupiter. This is a fundamental application of Newton's second law and the concept of weight variation across celestial bodies.

Question 17

A student observes that when a metal rod is heated at one end, the heat gradually spreads to the other end. Which of the following best explains this phenomenon and identifies the primary mode of heat transfer in solids?

Accepted Answer

In solids, heat transfer primarily occurs through conduction, where thermal energy is transferred from particle to particle through direct contact without any bulk movement of the material. In metals, free electrons also play a crucial role in rapid heat conduction, making metals excellent conductors of heat. This is why a metal rod heated at one end quickly becomes hot at the other end.

Question 18

In physics, the concept of 'work' is defined as the product of force and displacement in the direction of the force. If a constant force of 10 N is applied to move an object 5 meters in the direction of the force, how much work is done?

Accepted Answer

Work (W) is calculated using the formula W = F × d × cos(θ), where F is force, d is displacement, and θ is the angle between force and displacement. When force and displacement are in the same direction, θ = 0° and cos(0°) = 1, so W = F × d = 10 N × 5 m = 50 Joules (J).

Question 19

The speed of light in vacuum is a fundamental constant in physics, denoted by the symbol 'c'. What is the approximate value of the speed of light?

Accepted Answer

The speed of light in vacuum is approximately 3 × 10⁸ meters per second (m/s), or more precisely 299,792,458 m/s. This is one of the most important constants in physics and is used in Einstein's famous equation E = mc².

Question 20

According to Newton's Second Law of Motion, force is equal to mass multiplied by acceleration (F = ma). If an object of mass 5 kg experiences a net force of 20 N, what is its acceleration?

Accepted Answer

Using F = ma, we can rearrange to find acceleration: a = F/m = 20 N ÷ 5 kg = 4 m/s². This demonstrates the direct application of Newton's Second Law.

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Physics — Everyday Concepts — Practice Questions

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