TOP MCQ,s of physics all competitive examination.
With Hint in answer key.
1. An electron is moving north in a region when the magnetic field is south, the magnetic force exert on electron is
A):Zero.
B):Up
C):Down.
D):East
2.The ratio between velocity of sound in air at 4atm and that at 1atm pressure would be
A):4:1
B):1:4
C):3:1
D):1:1
3.wire of resistance 3.0 ohm is stretched to twice its original length the resistance of new wire will be:
A):3-ohm
B):1.5-ohm
C):6-ohm
D):12-ohm.
4.A basket ball is thrown upward along a parabolic path what is the ball acceleration at its highest point.
A):0
B):1/2-g-horizental.
C):g-upward
D):g-downward.
5.The relationship between resistance of wire and its diameter.
A):R is directly proportional to D
B):R is directly proportional to D-square.
C):R is inversely proportional to D
D):R is inversely proportional to D-square.
6.Three cells of 2 volt each are connected in series, the net voltage due to combination of cell is:
A):3-volt
B):1/3
C):6-volt
D):1/6
7.Which property is constant for a body in free fall.
A):Velocity.
B):Speed.
C):Displacement.
D):Acceleration.
8.In vacuum all electromagnetic wave have same:
A):Speed
B):Frequency.
C):wavelength.
D):Energy.
9.Which of the given formula would be used to calculate the wavelength of electron, given its velocity v---mass-m and constant lambda.
A):Lambda =hmv.
B):Lambda=h/mv.
C):Lambda=hv/m.
D):Lambda=v/hm.
10.Ohm,s law is valid only:
A):Thermistor.
B):Semiconductor.
C):Metal.
D):Bulb filament.
. . . . . . . . . Answer-key with hint
1-a--Hint--F=qvbsin(80)=0
2-d--Hint--V=underoot-rp/density.
3-c-Hint-R- is directly proportional to length.
4-d-Hint-Acceleration at highest point is g always down.
5.b.
6.c-Hint-(V=2v+2v+2v=6volt volt
7.d-Hing-acceleration in free fall g which is constant.
8.a-speed-Hint-all move with speed of light.
9-lambda=h/mv.
10.c-Metal.
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