- AHas its own persistent magnetic field.
- BActs as a magnet when an electric current passes through it.
- CBoth A and B.
- DNone of the above.
Explanation:
Electromagnets are a different from permanent magnets. Electromagnets are made of coils of wire with electricity passing through them.
When the coils of wire in an electromagnet have an electric current passing through them then magnetic field produced around the coils so the coils behave like a magnet.
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
If n drops, each of capacitance C, coalesce to form a single big drop, then the ratio of the energy stored in the big drop to that in each small drop will be
|
(a) n : 1 |
(b) n1/3 : 1 |
(c) n5/3 : 1 |
(d) n2 : 1 |
The half-life of radioactive Polonium (Po) is 138.6 days. For ten lakh Polonium atoms, the number of disintegrations in 24 hours is
|
(a) 2000 |
(b) 3000 |
(c) 4000 |
(d) 5000 |
E denotes electric field in a uniform conductor, I corresponding current through it,
drift velocity of electrons and P denotes thermal power produced in the conductor, then which of the following graph is incorrect
|
(a)
|
(b)
|
(c)
|
(d)
|

When the speed of a dc motor increases the armature current
|
(a) Increases |
|
(b) Decreases |
|
(c) Does not change |
|
(d) Increases and decreases continuously |
The nature of binding for a crystal with alternate and evenly spaced positive and negative ions is
|
(a) Covalent |
(b) Metallic |
(c) Dipolar |
(d) Ionic |
Radius of
nucleus is 3 Fermi. The radius of
nucleus will be
|
(a) 5 Fermi |
(b) 6 Fermi |
(c) 11.16 Fermi |
(d) 8 Fermi |
Two capacitors of capacities
and
are charged to voltages
and
respectively. There will be no exchange of energy in connecting them in parallel, if
|
(a) |
(b) |
(c) |
(d) |
Point charge
and
are kept at points x = 0 and x = 6 respectively. Electrical potential will be zero at points
|
(a) x = 2 and x = 9 |
(b) x = 1 and x = 5 |
(c) x = 4 and x = 12 |
(d) x = -2 and x = 2 |