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 Physics Questions

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Q:

No current will flow between two charged bodies if they have the same 

A) resistance B) charge
C) potential D) charge/ potential ratio
 
Answer & Explanation Answer: C) potential

Explanation:

An electric charge always flows from a body at higher potential to a body at a lower potential irrespective of the amounts of charges contained in them. In the question , no current flows. So there is no potential difference. 

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Q:

A periscope works by the principle of

A) Total internal reflection B) Refraction
C) Diffraction D) Reflection & Refraction
 
Answer & Explanation Answer: A) Total internal reflection

Explanation:

A periscope is an optical instrument that uses a system of prisms, lenses, or mirrors to reflect images through a tube.

 

 per11526634345.jpg image

 

Light from a distant object strikes the top mirror and is then reflected at an angle of 90 degrees down the periscope tube. At the bottom of the periscope, the light strikes another mirror and is then reflected into the viewer’s eye.

 

Hence, A periscope works by the principle of Total internal reflection.

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Q:

Ball bearings are used in cycles, scooters etc to

A) Increase the friction between the wheel and the axle B) Reduce the friction between the wheel and the axle
C) Reduce the friction between ground and the whee D) None of the above
 
Answer & Explanation Answer: B) Reduce the friction between the wheel and the axle

Explanation:
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Q:

What is the SI unit of pressure

A) Pascal B) Dyne
C) Newton D) Jule
 
Answer & Explanation Answer: A) Pascal

Explanation:
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Q:

The core of an electromagnet is made of soft iron because soft iron has 

A) small susceptibility and small retentivity B) large susceptibility and small retentivity
C) large density and large retentivity D) small density and large retentivity
 
Answer & Explanation Answer: B) large susceptibility and small retentivity

Explanation:
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Q:

Masses of stars and galaxies are usually expressed in terms of

A) neutron mass B) earth's mass
C) solar mass D) lunar mass
 
Answer & Explanation Answer: C) solar mass

Explanation:
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Q:

The working of the quartz crystal in the watch is based on the

A) Piezo - electric Effect B) Edison Effect
C) Photoelectric Effect D) Johnson Effect
 
Answer & Explanation Answer: A) Piezo - electric Effect

Explanation:
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Q:

The base of an electric iron is brightly polished mainly

A) to make it smooth and frictionless B) to make it rust-proof
C) to reduce heat loss by radiation D) to make it more durable
 
Answer & Explanation Answer: C) to reduce heat loss by radiation

Explanation:

Polished surfaces are poor radiators of heat. So loss of heat on that account is reduced and the electric iron remains hotter than otherwise.

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