- AC = C1 - C2
- BC = C1 + C2
- C1/C = 1/C1 + 1/C2
- D1/C = 1/C1 - 1/C2
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AB is a potentiometer wire of length 100 cm and its resistance is 10 ohms. It is connected in series with a resistance R = 40 ohms and a battery of e.m.f. 2 V and negligible internal resistance. If a source of unknown e.m.f. E is balanced by 40 cm length of the potentiometer wire, the value of E is

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(a) 0.8 V |
(b) 1.6 V |
(c) 0.08 V |
(d) 0.16 V |
The electric bulbs have tungsten filaments of same length. If one of them gives 60 watt and other 100 watt, then
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(a) 100 watt bulb has thicker filament |
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(b) 60 watt bulb has thicker filament |
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(c) Both filaments are of same thickness |
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(d) It is possible to get different wattage unless the lengths are different |
An ammeter of 100 W resistance gives full deflection for the current of 10–5 amp. Now the shunt resistance required to convert it into ammeter of 1 amp. range, will be
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(a) |
(b) |
(c) |
(d) |
A spherical surface of radius of curvature R separates air (refractive index 1.0) from glass (refractive index 1.5). The centre of curvature is in the glass. A point object P placed in air is found to have a real image Q in the glass. The line PQ cuts the surface at a point O, and PO = OQ. The distance PO is equal to
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(a) 5 R |
(b) 3 R |
(c) 2 R |
(d) 1.5 R |
An object placed 10 cm in front of a lens has an image 20 cm behind the lens. What is the power of the lens (in dioptres)
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(a) 1.5 |
(b) 3.0 |
(c) – 15.0 |
(d) + 15.0 |
Two cells when connected in series are balanced on 8m on a potentiometer. If the cells are connected with polarities of one of the cell is reversed, they balance on 2m. The ratio of e.m.f.'s of the two cells is
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(a) 3 : 5 |
(b) 5 : 3 |
(c) 3 : 4 |
(d) 4 : 3 |