A cathode emits 1.8 
electrons per second, when heated. When 400V is applied to anode all the emitted electrons reach the anode. The charge on electron is 1.6 
. The maximum anode current is
|
(a) 2.7 μA |
(b) 29 μA |
(c) 72 μA |
(d) 29 μA |
(b) 29 μA
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Assertion : The quantity L/R possesses dimensions of time.
Reason : To reduce the rate of increases of current through a solenoid should increase the time constant (L/R).
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If the assertion and reason both are false. |
Diamagnetic substances are
|
(a) Feebly attracted by magnets |
(b) Strongly attracted by magnets |
|
(c) Feebly repelled by magnets |
(d) Strongly repelled by magnets |
A step-up transformer has transformation ratio of 3 : 2. What is the voltage in secondary if voltage in primary is 30 V
| (a) 45 V | (b) 15 V |
(c) 90 V |
(d) 300 V |
If in a nuclear fusion process the masses of the fusing nuclei be 
and 
and the mass of the resultant nucleus be 
, then
(a) 
|
(b) 
|
(c) 
|
(d) 
|
Assertion : Short wave bands are used for transmission of ratio waves to a large distance
Reason : Short waves are reflected by ionosphere
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
| (d) If assertion is false but reason is true. |