Physics - General Knowledge Questions and Answers - in Hindi

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If the time taken for hearing the echo of a girl's voice after reflection from a cliff is 6 seconds, calculate the distance of the girl from cliff ?

A)

660 m


B)

1980 m


C)

330 m


D)

990 m



Correct Answer :

990 m


Explanation :

let girl is standing on A, then sound goes to the B cliff and then come back to A before she hear the sound.

time=6 sec, speed OF voice/sound=330 m/s

now, distance(AB+BA)= speed*time = 330*6 =1980 m

distance between the cliff = AB = BA

AB+BA = 1980
2AB = 1980
AB = 990 m

hence the distance of the girl from cliff 990 m

A dynamo converts ?

A)

electrical energy to mechanical energy


B)

electrical energy to magnetic energy


C)

chemical energy to electrical energy


D)

mechanical energy to electrical energy



Correct Answer :

mechanical energy to electrical energy


Explanation :

dynamo in Electrical Engineering
A dynamo is a device for converting mechanical energy into electrical energy. In a dynamo, the mechanical energy of rotation is converted into electrical energy in the form of a current in the armature.

It is an electrical generator that creates direct current(DC)

If the angle of incidence formed by a ray of light on a plane mirror is 37°, then the angle of refraction is?

A)

53°


B)

143°


C)

37°


D)

90°



Correct Answer :

37°


Explanation :

law of reflection - the angle of incidence is equal to the angle of reflection.

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