- A$\frac{ C }{ L }$
- B$\frac{1}{ RC }$
- ✓$\frac{ L }{ R }$
- D$\frac{ RL }{ C }$
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Two identical thin bar magnets each of length l and pole strength m are placed at right angle to each other with north pole of one touching south pole of the other. Magnetic moment of the system is
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(a) ml |
(b) 2ml |
(c) |
(d) |
The internal resistances of two cells shown are 0.1 Ω and 0.3 Ω. If R = 0.2 Ω, the potential difference across the cell
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(a) B will be zero |
(b) A will be zero |
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(c) A and B will be 2V |
(d) A will be > 2V and B will be < 2V |
When light is refracted from air into glass
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(a) Its wavelength and frequency both increase |
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(b) Its wavelength increases but frequency remains unchanged |
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(c) Its wavelength decreases but frequency remains unchanged |
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(d) Its wavelength and frequency both decrease |

Assertion : A loosely round helix made of stiff wire is suspended vertically with the lower end just touching a dish of mercury. When a current is passed through the wire, the helical wire executes oscillatory motion with the lower end jumping out of and inside of mercury.
Reason : When electric current is passed through helix, a magnetic field is produced both inside and outside the helix.
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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. |
A sphere of radius 1 cm has potential of 8000 V, then energy density near its surface will be
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(a) 64 |
(b) 8 |
(b) 8 |
(d) 2.83 |
Calculate the equivalent resistance between A and B
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(a) |
(b) 3 W |
(c) 6 W |
(d) |