(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.

(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?

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.

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

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.

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) Name the electromagnetic radiation used to detect fake currency. (b) Redraw the diagram given below and complete the path of the light ray AB through the glass prism till it emerges out of the prism. Critical angle of the glass is 42°.

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.

85 g of water at 30°C is cooled to 5°C by adding certain mass of ice. Find the mass of ice required. [Specific heat capacity of water = 4.2 J g−1 °C−1, Specific latent heat of fusion = 336 J g−1]

(a) State one factor that affects the magnitude of induced current in an AC generator. (b) Given below is a circuit to study the magnetic effect of electric current. ABCD is a cardboard kept perpendicular to the conductor XY. A magnetic compass is placed at the point P of the cardboard. P1 and P2 are the positions of the magnetic compass, before and after passing a current through XY respectively. (i) Name the rule that is used to predict the direction of deflection of the magnetic compass. (ii) State the direction of current in the conductor (X to Y or Y to X) when the circuit is complete. (iii) If resistance R is increased, then what will be the effect on the magnetic lines of force around the conductor?