Question
Photoelectric effect was successfully explained first by
|
(a) Planck |
(b) Hallwash |
(c) Hertz |
(d) Einstein |
✓
Answer
(d) Einstein
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
The moment of inertia of a uniform semicircular wire of mass M and radius r about a line perpendicular to the plane of the wire through the centre is:
→-
$\text{Mr}^2$
-
$\frac{1}{2}\text{Mr}^2$
-
$\frac{1}4{}\text{Mr}^2$
-
$\frac{2}{5}\text{Mr}^2$
Which of the following particles will describe the smallest circle when projected with the same velocity perpendicular to a magnetic field?
- Electron
- Proton
- He+
- Li+
Relation between principal quantum number ' $n$ ' and radius $r_n$ of Bohr's orbit is:
→When a forward bias is applied to a p-n juction it ___________ .
In radio theraphy, X-rays are used to
| (a) Detect bone fractures |
(b) Treat cancer by controlled exposure |
| (c) Detect heart diseases | (d) Detect fault in radio receiving circuits |
Earth is the source of __________?
A metal rod moves at a constant velocity in a direction perpendicular to its length. A constant uniform magnetic field exists in space in a direction perpendicular to the rod as well as its velocity. Select the correct statement(s) from the following
|
(a) The entire rod is at the same electric potential |
|
(b) There is an electric field in the rod |
|
(c) The electric potential is highest at the centre of the rod and decreases towards its ends |
|
(d) The electric potential is lowest at the centre of the rod and increases towards its ends |
The focal length of objective and eye lens of a microscope are 4 cm and 8 cm respectively. If the least distance of distinct vision is 24 cm and object distance is 4.5 cm from the objective lens, then the magnifying power of the microscope will be
|
(a) 18 |
(b) 32 |
(c) 64 |
(d) 20 |
In the figure shown there are two semicircles of radii 
and 
in which a current i is flowing. The magnetic induction at the centre O will be
|
(a) |
(b) |
(c) |
(d) |
Second law of Kirchhoff depends on the principle of conservation of: