Physics - Study Mode

[#956] An object which absorbs all colours and reflects none appears:
Correct Answer

(D) Black

Explanation

Solution: A black object absorbs all wavelengths of light and reflects none and that's why it appears black. Consequently, black absorbs the most heat.

[#957] Microphone is a device which transforms the
Correct Answer

(A) Sound signal into current signal

Explanation

Solution: Microphone is a device which transforms the sound signal into current signal.

[#958] Conversion of heat into electrical energy is achieved by using :
Correct Answer

(D) Thermocouple

Explanation

Solution: Conversion of heat into electrical energy is achieved by using thermocouple.

[#959] How much calorie of energy is released by a boiled egg ?
Correct Answer

(D) 77

Explanation

Solution: 77-78 calories are released in a large size boiled egg.

[#960] A 4 kg object is moving horizontally with a speed of 5 m/s. To increase its speed to 10 m/s, the amount of net work required to be done on this object is:
Correct Answer

(A) 150 J

Explanation

Solution: m=4 kg u=5 m/s v=10 m/s according to work energy theorem w=1/2*m*(v 2 -u 2 ) w=1/2*4*(10 2 -5 2 ) w=1/2*4*(100-25) w=2×75 w=150 J