- AThe presence of electrons
- BThe presence of holes
- CThe presence of both electrons and holes
- DNone of the above
Explanation:
In the valence band, current is only due to holes. In the conduction band, current is due to electrons.
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A capacitor having capacitance C is charged to a voltage V. It is then removed and connected in parallel with another identical capacitor which is uncharged. The new charge on each capacitor is now
|
(a) CV |
(b) CV / 2 |
(c) 2 CV |
(d) CV / 4 |
If m1 and m2 are the refractive indices of the materials of core and cladding of an optical fibre, then the loss of light due to its leakage can be minimised by having
|
(a) m1 > m2 |
(b) m1 < m2 |
(c) m1 = m2 |
(d) None of these |
A radioactive substance emits
|
(a) Electromagnetic radiation |
(b) Electrons revolving around the nucleus |
|
(c) Charged particles |
(d) a,c |
A bar magnet when placed at an angle of 30o to the direction of magnetic field induction of 5 × 10–2 T, experiences a moment of couple 25 × 10–6 N-m. If the length of the magnet is 5 cm its pole strength is
|
(a) 2 × 10–2 A-m |
(b) 5 × 10–2 A-m |
(c) 2 A-m |
(d) 5 A-m |
To convert a 800 mV range milli voltmeter of resistance 40 W into a galvanometer of 100 mA range, the resistance to be connected as shunt is
|
(a) 10 W |
(b) 20 W |
(c) 30 W |
(d) 40 W |
If m, mn and mp are the masses of
nucleus, neutron and proton respectively
|
(a) |
(b) |
|
(c) |
(d) |
Wave nature of light follows because
|
(a) Light rays travel in a straight line |
|
(b) Light exhibits the phenomena of reflection and refraction |
|
(c) Light exhibits the phenomenon of interference |
|
(d) Light causes the phenomenon of photoelectric effect |
If a magnetic substance is kept in a magnetic field, then which of the following is thrown out
|
(a) Paramagnetic |
(b) Ferromagnetic |
(c) Diamagnetic |
(d) Antiferromagnetic |