- AAm-2, [A1L-2]
- BAm2, [A1L2]
- CAm-1, [A1L-1]
- DAm1, [A1L1]
Explanation:
Current density is the amount of charge flowing per second through a unit area.
The SI unit of current density is ampere per square metre (Am-2) and its dimensions are [A1L-2].
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Assertion : In Hertz experiment, the electric vector of radiation produced by the source gap is parallel to the gap.
Reason : Production of sparks between the detector gap is maximum when it is placed perpendicular to the source gap.
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(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
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(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
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(c) If assertion is true but reason is false. |
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(d) If the assertion and reason both are false. |
Light of two different frequencies whose photons have energies 1eV and 2.5eV respectively, successively illuminates a metal of work function 0.5eV. The ratio of maximum kinetic energy of the emitted electron will be
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(a) 1 : 5 |
(b) 1 : 4 |
(c) 1 : 2 |
(d) 1 : 1 |
The resistance of a 5 cm long wire is 10 W. It is uniformly stretched so that its length becomes 20 cm. The resistance of the wire is
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(a) 160 W |
(b) 80 W |
(c) 40 W |
(d) 20 W |
The half-life of a radioactive substance is 3.6 days. How much of 20 mg of this radioactive substance will remain after 36 days
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(a) 0.0019 mg |
(b) 1.019 mg |
(c) 1.109 mg |
(d) 0.019 mg |
A circular metal plate of radius R is rotating with a uniform angular velocity ω with its plane perpendicular to a uniform magnetic field B. Then the emf developed between the centre and the rim of the plate is
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(a) πω |
(b) ω |
(c) πω |
(d) ω |
Light of wavelength
strikes a photo-sensitive surface and electrons are ejected with kinetic energy E. If the kinetic energy is to be increased to 2E, the wavelength must be changed to
where
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(a) |
(b) |
(c) |
(d) |