The image formed by a concave mirror:
- AIs always real.
- BIs always virtual.
- CIs certainly real if the object is virtual.
- DIs certainly virtual if the object is real.
The image formed by a concave mirror:
Explanation:
| Object | Image |
| O1 | I1 |
| O2 | I2 |
| O3 | I3 |
| O4 | I4 |
Here O4 is virtual oblect & I4 is real image.

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A short bar magnet placed with its axis at 30° with a uniform external magnetic field of 0.16 Tesla experiences a torque of magnitude 0.032 Joule. The magnetic moment of the bar magnet will be
|
(a) 0.23 Joule/Tesla |
(b) 0.40 Joule/Tesla |
(c) 0.80Joule/Tesla |
(d) Zero |
To obtain P-type Si semiconductor, we need to dope pure Si with
|
(a) Aluminium |
(b) Phosphorous |
(c) Oxygen |
(d) Germanium |
$\frac{1}{\text{v}}-\frac{1}{\text{u}}=\frac{1}{\text{uf}}$
$\frac{1}{\text{v}^2}-\frac{1}{\text{u}}=\frac{1}{\text{f}}$
$\frac{1}{\text{v}-\text{t}}-\frac{1}{\text{u}+\text{t}}=\frac{1}{\text{f}}$
$\frac{1}{\text{v}}-\frac{1}{\text{u}}+\frac{\text{t}}{\text{uv}}=\frac{\text{t}}{\text{f}}$
A coil resistance 20W and inductance 5H is connected with a 100V battery. Energy stored in the coil will be
|
(a) 41.5 J |
(b) 62.50 J |
(c) 125 J |
(d) 250 J |
If a 2 kW boiler is used everyday for 1 hour, then electrical energy consumed by boiler in thirty days is
|
(a) 15 unit |
(b) 60 unit |
(c) 120 unit |
(d) 240 unit |
The distance between the two charges 25μC and 36μC is 11 cm At what point on the line joining the two, the intensity will be zero
|
(a) At a distance of 5 cm from 25 μC |
(b) At a distance of 5 cm from 36 μC |
|
(c) At a distance of 10 cm from 25 μC |
(d) At a distance of 11 cm from 36 μC |