Explanation:
The magnetic susceptibility of diamagnetic materials doesn’t depend upon temperature. This is often because there’s an outsized barrier between the bottom state and therefore the excited states of diamagnetic substances. Hence, it remains constant during the change of temperature. All the other statements are false.
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The energy that should be added to an electron to reduce its de Broglie wavelength from one nm to 0.5 nm is
|
(a) Four times the initial energy |
(b) Equal to the initial energy |
|
(c) Twice the initial energy |
(d) Thrice the initial energy |
The plates of a capacitor are charged to a potential difference of 320 volts and are then connected across a resistor. The potential difference across the capacitor decays exponentially with time. After 1 second the potential difference between the plates of the capacitor is 240 volts, then after 2 and 3 seconds the potential difference between the plates will be
|
(a) 200 and 180 V |
(b) 180 and 135 V |
(c) 160 and 80 V |
(d) 140 and 20 V |
As the temperature of hot junction of a thermo‑couple is increased (while cold junction is at constant temperature), the thermo e.m.f.
|
(a) Increases uniformly at constant rate |
|
(b) Increases slowly in the beginning and more rapidly at higher temperatures |
|
(c) Increases more rapidly in the beginning but less rapidly at higher temperatures |
|
(d) In minimum at neutral temperature |
How many calories of heat will be produced approximately in a 210 watt electric bulb in 5 minutes
|
(a) 80000 cal |
(b) 63000 cal |
(c) 1050 cal |
(d) 15000 cal |
The focal length of a convex mirror is 20 cm its radius of curvature will be
|
(a) 10 cm |
(b) 20 cm |
(c) 30 cm |
(d) 40 cm |
The half life period of a radioactive substance is 5 min. The amount of substance decayed in 20 min will be
|
(a) 93.75% |
(b) 75% |
(c) 25% |
(d) 6.25% |