Explanation:
Fusion reaction takes place at temperatures around 107k. It requires this high temperature so that nucleus start moving at rapidly speed, which in turn increases their kinetic, so that they overcome the repulsion between them and can come together.
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A achromatic combination is made with a lens of focal length f and dispersive power ω with a lens having dispersive power of 2ω. The focal length of second will be
|
(a) 2f |
(b) f/2 |
(c) -f/2 |
(d) – 2 f |
The capacity of an air condenser is 2.0 mF. If a medium is placed between its plates. The capacity becomes 12 mF. The dielectric constant of the medium will be
|
(a) 5 |
(b) 4 |
(c) 3 |
(d) 6 |
There are 8 equal resistances R. Two are connected in parallel, such four groups are connected in series, the total resistance of the system will be
|
(a) R / 2 |
(b) 2 R |
(c) 4 R |
(d) 8 R |
The inductance of a coil is 60μH. A current in this coil increases from 1.0 A to 1.5 A in 0.1 second. The magnitude of the induced e.m.f. is
|
(a) 60 |
(b) 300 |
(c) 30 |
(d) 3 |
The frequencies of X-rays, g-rays and ultraviolet rays are respectively a, b and c. Then
|
(a) a < b, b > c |
(b) a > b, b > c |
(c) a > b, b < c |
(d) a < b, b < c |
$\text{v}_1=\text{v}_2$
$\text{v}_1=13.6\text{v}_2$
$\text{v}_1=\frac{\text{v}_2}{\text{13.6}\cdot}$
$\text{v}_1=\sqrt{13.6}\text{v}_2$
A convex mirror of focal length f forms an image which is 
times the object. The distance of the object from the mirror is
|
(a) (n – 1)f |
(b) |
(c) |
(d) (n + 1)f |
A thin lens is made with a material having refractive index $\mu=1.5.$ Both the sides are convex. It is dipped in water $(\mu=1.33).$ It will behave like:
A radio transmitter operates at a frequency of 880 kHz and a power of 10 kW. The number of photons emitted per second are
|
(a) 1.72 |
(b) 1327 |
(c) 13.27 |
(d) 0.075 |
