Explanation:
The magnetic field associated with a coil is the magnetic flux flowing normally to the surface area of the current-carrying coil. When it changes, an emf is produced opposing the cause. This is the principle of Electromagnetic induction.
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Assertion : X-ray travel with the speed of light.
Reason : X-rays are electromagnetic rays.
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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. |
The contribution in the total current flowing through a semiconductor due to electrons and holes are 
and 
respectively. If the drift velocity of electrons is 
times that of holes at this temperature, then the ratio of concentration of electrons and holes is
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(a) 6 : 5 |
(b) 5 : 6 |
(c) 3 : 2 |
(d) 2 : 3 |
Which of one is correct
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(a) |
(b) |
(c) |
(d) |
The equivalent quantity of mass in electricity is
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(a) Charge |
(b) Potential |
(c) Inductance |
(d) Current |
The amplification produced by a triode is due to the action of
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(a) Filament |
(b) Cathode |
(c) Grid |
(d) Plate |
A small coil C with N = 200 turns is mounted on one end of a balance beam and introduced between the poles of an electromagnet as shown in figure. The cross sectional area of coil is A= 1.0 cm2, length of arm OA of the balance beam is l = 30 cm. When there is no current in the coil the balance is in equilibrium. On passing a current I = 22 mA through the coil the equilibrium is restored by putting the additional counter weight of mass ∆m = 60 mg on the balance pan. Find the magnetic induction at the spot where coil is located.
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(a) 0.4 T |
(b) 0.3 T |
(c) 0.2 T |
(d) 0.1 T |
The typical ionisation energy of a donor in silicon is
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(a) 10.0 eV |
(b) 1.0eV |
(c) 0.1 eV |
(d) 0.001 eV |
In the CB mode of a transistor, when the collector voltage is changed by 0.5 volt. The collector current changes by 0.05 mA. The output resistance will be
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(a) 10 kW |
(b) 20 kW |
(c) 5 kW |
(d) 2.5 kW |
If current flowing through shell of previous objective is equal to i, then energy density at a point distance 2R from axis of the shell varies according to the graph
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(a)
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(b)
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(c)
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(d)
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The capacity of parallel plate condenser depends on
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(a) The type of metal used |
(b) The thickness of plates |
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(c) The potential applied across the plates |
(d) The separation between the plates |
