Multiple Choice QuestionsA photon is incident having frequency 1 x 10 sec-1. Threshold frequency of metal is 5 x 1013 sec-1. Find the kinetic energy of the ejected electron.
3.3 × 10-21 J
6.6 × 10-21 J
3.3 × 10-20 J
6.6 × 10-20 J
Find the voltage drop across a capacitor connected with a resistance and a battery of 60 V in series after a long time.
0V
60 V
30 V
38 V
A galvanometer has a current sensitivity of 1 mA per division. A variable shunt is connected across the galvanometer and the combination is put in series with a resistance of 500 Ω and cell of internal resistance 1 Ω It gives a deflection of 5 division for shunt of 5 ohm and 20 division for shunt of 25 ohm. The emf of cell is
47.1 V
57.1 V
67.1 V
77.1 V
Assertion: It is advantageous to transmit electric power at high voltage.
Reason: High voltage implies high current.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
The dimensions of specific resistance are
[ M L2 T-2 A-1 ]
[ M L3 T-3 A-2 ]
[ M L3 T-2 A-1 ]
[ M L2 T-2 A-2 ]
Assertion: The dimensional formula for product of resistance and conductance is same as for dielectric constant.
Reason: Both have dimension of time costant.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
A bulb of 25 W. 200 V and another bulb of 100 W, 200 V are connected in series with a supply line of 220 V. Then
both bulbs will glow with same brightness
both bulbs will get fused
25 W bulb will glow more brightly
100 W bulb will glow more brightly
Assertion: A bird perches on a high power line and nothing happens to the bird.
Reason: The level of bird is very high from the ground.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
C.
If assertion is true but reason is false
Electric shock is due to the electric current flowing through a living body. When the bird perches on a single high power line, no current passes through its body because its body is at equipotential surface i.e., there is no potential difference. While when man touches the same line, standing bare foot on ground the electrical circuit is completed through the ground. The hands of man are at high potential and his feets are at low potential. Hence large amount of current flows through the body of the man and person therefore gets a fatal shock.
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