Physics - Study Mode

[#821] Night photography and photopraphy in mist and fog are possible using
Correct Answer

(B) Infra-red radiation

Explanation

Solution: Infrared is used in night vision equipment when there is insufficient visible light to see. Night vision devices operate through a process involving the conversion of ambient light photons into electrons which are then amplified by a chemical and electrical process and then converted back into visible light.

[#822] A car parked in the sun with its windows closed gets terribly hot inside. This is due to
Correct Answer

(B) The greenhouse effect

Explanation

Solution: The inside of a car with its windows closed is hotter than outside due to green house effect as the glass in the windows absorb infrared radiations of the sun but do not allow them to escape or reflect back, thus increasing the temperature of the car on the inside.

[#823] To measure the speed of an approaching car a police officer shines
Correct Answer

(C) Radio waves on it

Explanation

Solution: Radar, which stands for radio detection and ranging, is a system that uses reflected radio waves to detect objects and measure their distance and speed. For example, police use radar to calculate the speed of cars.

[#824] The device used for measuring the wavelength of X-rays is
Correct Answer

(C) Bragg Spectrometer

Explanation

Solution: The device used for measuring the wavelength of X-rays is Bragg Spectrometer.

[#825] If the wavelengths corresponding to ultraviolet, visible and infrared radiations are given as lUV, lVIS and lIR respectively, then which of the following gives the correct relationship among these wavelengths?
Correct Answer

(D) LUV < lVIS < lIR

Explanation

Solution: The correct relationship among these wavelengths is
LUV < lVIS < lIR.