Explanation:
Charge distribution or M, A & B
So, we can say that M attracts A, M attracts B, A attracts B and 'B' attracts A.
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Assertion : Current is passed through a metallic wire, heating it red. When cold water is poured on half of its portion, then rest of the half portion become more hot.
Reason : Resistances decreases due to decrease in temperature and so current through wire increases.
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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. |
There are three voltmeters of the same range but of resistances 1000Ω, 8000 Ω and 4000 Ω respectively. The best voltmeter among these is the one whose resistance is
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(a) 10000 W |
(b) 8000 W |
(c) 4000 W |
(d) All are equally good |
The idea of the quantum nature of light has emerged in an attempt to explain
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(a) Interference |
(b) Diffraction |
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(c) Radiation spectrum of a black body |
(d) Polarisation |
Monochromatic green light of wavelength 5 
illuminates a pair of slits 1 mm apart. The separation of bright lines on the interference pattern formed on a screen 2 m away is
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(a) 0.25 mm |
(b) 0.1 mm |
(c) 1.0 mm |
(d) 0.01 mm |
If a hole is made at the centre of a bar magnet, then its magnetic moment will
| (a) Increase | (b) Decrease | (c) Not change | (d) None of these |
Electric charges of +10μC, + 5μC, -3μC and +8 μC are placed at the corners of a square of side 
m. the potential at the centre of the square is
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(a) 1.8 V |
(b) |
(c) 1.8 |
(d) 1.8 |
A convex lens makes a real image 4 cm long on a screen. When the lens is shifted to a new position without disturbing the object, we again get a real image on the screen which is 16 cm tall. The length of the object must be
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(a) 1/4 cm |
(b) 8 cm |
(c) 12 cm |
(d) 20 cm |
A circular loop of radius R carrying current I lies in x-y plane with its centre at origin. The total magnetic flux through x-y plane is
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(a) Directly proportional to I |
(b) Directly proportional to R |
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(c) Directly proportional to |
(d) Zero |
Correct relation for triode is
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(a) |
(b) μ = |
(c) μ = |
(d) None of these |
