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3 years ago

What type of surface is a poor reflector but a good absorber of radiation

Physics

1 answer:

koban [17]3 years ago

3 0

Black surface is the best absorber of radiations but a poor reflector.

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An electron is released from rest on the axis of a uniform positively charged ring, 0.200 m from the ring's center. If the linea

melisa1 [442]

Answer:

Velocity of the electron at the centre of the ring, $v=1.37\times10^7\ \rm m/s$

Explanation:

<u>Given:</u>

Linear charge density of the ring= $0.1\ \rm \mu C/m$
Radius of the ring R=0.2 m
Distance of point from the centre of the ring=x=0.2 m

Total charge of the ring

$Q=0.1\times2\pi R\\Q=0.1\times2\pi 0.4\\Q=0.251\ \rm \mu C$

Potential due the ring at a distance x from the centre of the rings is given by

$V=\dfrac{kQ}{\sqrt{(R^2+x^2)}}\\$

The potential difference when the electron moves from x=0.2 m to the centre of the ring is given by

$\Delta V=\dfrac{kQ}{R}-\dfrac{kQ}{\sqrt{(R^2+x^2)}}\\\Delta V={9\times10^9\times0.251\times10^{-6}} \left( \dfrac{1}{0.4}-\dfrac{1}{\sqrt{(0.4^2+0.2^2)}} \right )\\\Delta V=5.12\times10^2\ \rm V$

Let $\Delta U$ be the change in potential Energy given by

$\Delta U=e\times \Delta V\\\Delta U=1.67\times10^{-19}\times5.12\times10^{2}\\\Delta U=8.55\times10^{-17}\ \rm J$

Change in Potential Energy of the electron will be equal to the change in kinetic Energy of the electron

$\Delta U=\dfrac{mv^2}{2}\\8.55\times10^{-17}=\dfrac{9.1\times10^{-31}v^2}{2}\\v=1.37\times10^7\ \rm m/s$

So the electron will be moving with $v=1.37\times10^7\ \rm m/s$

5 0

3 years ago

A 20-kg cart travels at 20 m/s in a circle with a radius of 20 m. What is the centripetal force?

Vlad1618 [11]

Centripetal force = (mass) x (speed)² / (radius)

   = (20 kg) x (20 m/s)² / (20 m)

   = (20 x 20 / 20) (kg-meter/sec²)

   = 20 newtons

5 0

3 years ago

Read 2 more answers

The rate at which the earth's surface loses heat and keeps earth temperature at which living things can survive

agasfer [191]

<span>I believe it's insulation.</span>

5 0

3 years ago

What is the highest temperature ever recorded on earth

Llana [10]

Therefore the world's record high temperature of 134.0°F (56.7°C) is held by Furnace Creek Ranch in Death Valley, California. That global high temperature was attained on July 10, 1913.

4 0

3 years ago

Does sand stay sand forever?

Gemiola [76]

Answer:

No sand doesn't stay sand forever.

Explanation:

We may have a thought that the sand we see on the beach areas are always the same one for eternal, but it is not true.
Due to different activities like beach nourishment, sand replenishment etc. the sand in the beach areas are changed and replaced.
If the sand remained there for long time, it also affects the sand eating organisms and plants.

3 0

3 years ago