Physics - Study Mode

[#1136] Light from the sun reaches us in nearly
Correct Answer

(C) 8 minutes
(G) 8 min

Explanation

Solution: The light from the sun takes about 8 minutes to reach the Earth after it has been emitted from the sun's surface. The time it takes for light to reach planets in our Solar System varies from about 3 minutes for Mercury to about 5.3 hours for Pluto.

[#1137] An image formed by a plane mirror, that cannot be obtained on a screen is called ________
Correct Answer

(A) Virtual image

Explanation

Solution: A virtual image is formed when reflected rays appear to meet. Such images cannot be obtained on screen. Plane mirrors, convex mirror and concave lens always forms virtual image.

[#1138] Which of the following is a device designed to protect electrical devices from voltage spikes?
Correct Answer

(B) Surge protector

Explanation

Solution: Surge Protection Device (or surge suppressor or surge diverter) is an appliance or device designed to protect electrical devices from voltage spikes. A surge protector attempts to limit the voltage supplied to an electric device by either blocking or shorting to ground any unwanted voltages above a safe threshold.

[#1139] The working of the quartz crystal in the watch is based on the
Correct Answer

(A) Piezo - electric Effect

Explanation

Solution: The quartz crystal oscillates (vibrates back and forth) at a precise frequency: exactly 32768 times each second. This is due to Piezoelectric Effect. Piezoelectric Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress.

[#1140] The device which transfer the signal from low resistance region to high resistance region is
Correct Answer

(B) Transistor

Explanation

Solution: A transistor transfers a signal from a low resistance to high resistance. It has two PN-junctions: one junction is forward biased and other junction is reverse biased having low resistance path and high resistance path respectively. The weak signal is introduced in the low resistance, circuit and output is taken from the high resistance circuit.