Two identical cells send the same current in 2Ω resistance, whether connected in series or in parallel. The internal resistance of the cell should be
|
(a) 1 Ω |
(b) 2 Ω |
(c) |
(d) 2.5 Ω |
(b) 2 Ω
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The current in a simple series circuit is 5.0 amp. When an additional resistance of 2.0 ohms is inserted, the current drops to 4.0 amp. The original resistance of the circuit in ohms was
|
(a) 1.25 |
(b) 8 |
(c) 10 |
(d) 20 |
A radioactive substance emits
|
(a) Electromagnetic radiation |
(b) Electrons revolving around the nucleus |
|
(c) Charged particles |
(d) a,c |
In the absence of an electric field, the mean velocity of free electrons in a conductor at absolute temperature (T) is:
In Young's double slit experiment using sodium light (λ = 5898 Å), 92 fringes are seen. If given colour (λ = 5461 Å) is used, how many fringes will be seen
|
(a) 62 |
(b) 67 |
(c) 85 |
(d) 99 |
Assertion : Free electron always keep on moving in a conductor even then no magnetic force act on them in magnetic field unless a current is passed through it.
Reason : The average velocity of free electron is zero.
|
(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. |
A uniform wire of resistance R is uniformly compressed along its length, until its radius becomes n times the original radius. Now resistance of the wire becomes
|
(a) |
(b) |
(c) |
(d) nR |
Two point charges (+Q) and (-2Q) are fixed on the X-axis at positions a and 2a from origin respectively. At what positions on the axis, the resultant electric field is zero
|
(a) Only x = |
(b) Only x = - |
(c) Both x = ± |
(d) x = |
