- AIron
- BCobalt
- CCopper
- DNickel
Explanation:
A magnet is a material that has both attractive and directive properties. It attracts small pieces of iron, nickel, cobalt, etc. This property of attraction is called magnetism. Going by this criteria, copper is not attracted by magnets.
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When an electron in hydrogen atom is excited, from its 4th to 5th stationary orbit, the change in angular momentum of electron is (Planck’s constant: h = 6.6
|
(a) 4.16 |
(b) 3.32 |
|
(c) 1.05 |
(d) 2.08 |

Two sources of equal emf are connected to an external resistance R. The internal resistances of the two sources are and
. If the potential difference across the source having internal resistance
is zero, then
|
(a) |
(b) |
|
(c) |
(d) |
If
and
are the number of electrons and holes in a semiconductor heavily doped with phosphorus, then
|
(a) |
(b) |
(c) |
(d) |
Zener diode is used as
|
(a) Half wave rectifier |
(b) Full wave rectifier |
|
(c) ac voltage stabilizer |
(d) dc voltage stabilizer |
The energy of the highest energy photon of Balmer series of hydrogen spectrum is close to
| (a) 13.6 eV | (b) 3.4 eV | (c) 1.5 eV | (d) 0.85 eV |