The magnetic susceptibility of any paramagnetic material changes with absolute temperature T as
|
(a) Directly proportional to T |
(b) Remains constant |
|
(c) Inversely proportional to T |
(d) Exponentially decaying with T |
(c) Inversely proportional to T
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The dispersive power of the material of lens of focal length 20 cm is 0.08. The longitudinal chromatic aberration of the lens is
|
(a) 0.08 cm |
(b) 0.08/20 cm |
(c) 1.6 cm |
(d) 0.16 cm |
A person cannot see distinctly at the distance less than one metre. Calculate the power of the lens that he should use to read a book at a distance of 25 cm
|
(a) + 3.0 D |
(b) + 0.125 D |
(c) – 3.0 D |
(d) + 4.0 D |
A copper wire of length 1 m and radius 1 mm is joined in series with an iron wire of length 2 m and radius 3 mm and a current is passed through the wires. The ratio of the current density in the copper and iron wires is
|
(a) 18 : 1 |
(b) 9 : 1 |
(c) 6 : 1 |
(d) 2 : 3 |
For the Bohr's first orbit of circumference 2πr, the de-Broglie wavelength of revolving electron will be
|
(a) 2πr |
(b) πr |
(c) |
(d) |
Assertion : Bohr had to postulate that the electrons in stationary orbits around the nucleus do not radiate.
Reason : According to classical physics all moving electrons radiate.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If the assertion and reason both are false. |
A solenoid is 1.5 m long and its inner diameter is 4.0 cm. It has three layers of windings of 1000 turns each and carries a current of 2.0 amperes. The magnetic flux for a cross-section of the solenoid is nearly
|
(a) 2.5 × 10–7 weber |
(b) 6.31 × 10–6 weber |
(c) 5.2 × 10–5 weber |
(d) 4.1 × 10–5 weber |
