Assertion: Tiny air molecules scatter blue light more than red light. Reason: The refractive index of air is greater for blue light than for red light. (a) Both Assertion and Reason are true and Reason is the correct explanation of Assertion. (b) Both Assertion and Reason are false. (c) Assertion is true but Reason is false. (d) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.

A blackened thermometer bulb placed beyond the red end of a spectrum shows a rise in temperature due to: (a) infrared radiations (b) ultraviolet radiations (c) X-rays (d) radio waves

(a) Infrared radiations are used in warfare. Explain with reason, why. (b) A ray of light is incident at 45° on an equilateral prism in the diagram below. (1) Name the phenomenon exhibited by the ray of light when it enters and emerges out of the prism. (2) State the cause of the above phenomenon mentioned by you.

The diagram below shows two parallel rays A (Orange) & B (Blue) incident from air, on air-glass boundary. (a) Copy and complete the path of the rays A and B. (b) How do the speeds of these rays differ in glass?(c) Are the two refracted rays in glass parallel? Give a reason.

The diagram below shows the ray OP travelling through an equilateral prism of a certain material. (a) Calculate the value of i2, if the angle of deviation is 43°. (b) What is the ray QS called?

(a) Name the radiations: (1) for which a quartz prism is used to study the spectrum. (2) which are used in remote sensing devices. (3) which are used in traffic signals in India. (b) Name one property common to all electromagnetic radiations.

(a) Why do we use red colour as a danger signal on the top of a skyscraper? (b) The diagram below shows the path of a blue ray through the prism: (i) Calculate the critical angle of the material of the prism for blue colour. (ii) What is the measure of the angle of this prism (A)? (iii) Which colour should replace the blue ray, for the ray to undergo Total Internal Reflection?

Assertion (A): Ultraviolet radiations are scattered more as compared to the microwave radiations. Reason (R): Wavelength of ultraviolet radiation is more than the wavelength of microwave radiation. (a) Both A and R are true. (b) A is true but R is false. (c) A is false but R is true. (d) Both A and R are false.

Which one of the following combinations is the correct ascending order of electromagnetic waves in terms of wavelength? (a) Gamma-rays, visible light, microwaves (b) Microwaves, visible light, gamma-rays (c) Gamma-rays, microwaves, visible light (d) Microwaves, gamma-rays, visible light

Below is an incomplete table showing the arrangement of electromagnetic spectrum in the increasing order of their wavelength. Complete the table. Gamma ray X-ray U V rays Visible rays Infrared A Radio waves (a) Identify the radiation A. (b) Name the radiation used to detect fracture in bones. (c) Name one property common to both A and Radio waves.

Two persons A and B are standing in front of a cliff in the same line, 170 m apart, as shown in the diagram. Person B fires a gun and hears the echo in 3 s. Then person A, standing in front of B, fires the gun. (Speed of sound in air = 340 m s−1) (a) Calculate: (1) the distance of B from the cliff; (2) the minimum time in which B hears the gunshot fired by A. (b) Fill in the blank: The echo is softer than the original sound due to the decrease in ............... [amplitude / frequency] of the wave.

A ball of mass 20 g falls from a height of 45 m. It rebounds from the ground to a height of 40 m. Calculate: (a) initial potential energy of the ball. (b) the speed of the ball at which it hits the ground. (c) the loss in kinetic energy on striking the ground. [g = 10 m s−2]