- AThe law of conservation of momentum.
- BThe law of conservation of charge.
- CThe law of conservation of energy.
- DThe law of conservation of emf.
Explanation:
Lenz's law states that the current induced in a circuit due to a change or a motion in a magnetic field is so directed as to oppose the change in flux.
We know that induced EMF produces a current that opposes the change in flux, because a change in flux means a change in energy.Energy can enter or leave, but not instantaneously. So, Lenz' law is a consequence of the law of conservation of energy.
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Field at the centre of a circular coil of radius r, through which a current I flows is
|
(a) Directly proportional to r |
(b) Inversely proportional to I |
|
(c) Directly proportional to I |
(d) Directly proportional to |
A person A can clearly see objects between 25cm and 200cm. Which of the following may represent the range of clear vision for a person B having muscles stronger than A, but all other parameters of eye identical to that of A?
Order of q/m ratio of proton, α -particle and electron is
|
(a) e > p > α |
(b) p > α > e |
(c) e > α > p |
(d) None of these |
If work function of metal is 3eV then threshold wavelength will be
|
(a) 4125 Å |
(b) 4000 Å |
(c) 4500 Å |
(d) 5000 Å |
A plane electromagnetic wave is incident on a material surface. If the wave delivers momentum p and energy E, then
| (a) p = 0, E = 0 | (b) p ¹ 0, E ¹ 0 | (c) p ¹ 0, E = 0 | (d) p = 0, E ¹ 0 |