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3 years ago

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Calculate the recombination rate if the excess carrier concentration is 1014cm-3 and the carrier lifetime is 1usec. (a) 108 (b)

1010 (c) 1020 (d) 1014

1 answer:

Drupady [299]3 years ago

5 0

Answer:

$10^{20}\frac{cm^{-3}}{sec}$

Explanation:

The recombination rate is denoted by R it is the ratio of excess carrier concentration and life time

The recombination rate R is given by $R=\frac{\Delta n}{\tau _n}$

We have given excess carrier concentration = $10^{14}cm^-3$

Life time $\tau _n=10^{-6}sec$

So recombination rate $R=\frac{\Delta n}{\tau _n}=\frac{10^{14}}{10^{-6}}=10^{20}\frac{cm^{-3}}{sec}$

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Answer:

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P = 23.14 Watt

Explanation:

given,

mass of automobile = 1200 kg

velocity = 50 km/h

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kinetic energy = $\dfrac{1}{2}mv^2$

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K.E = 115.93 k J

vehicle accelerated to velocity = 100 km/h

= 100 × 0.2778

= 27.78 m/s

kinetic energy = $\dfrac{1}{2}mv^2$

= $\dfrac{1}{2}\times 1200 \times 27.78^2$

K.E = 463.04 k J

work done = change in kinetic energy

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= 347.11 J

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Power = $\dfrac{347.11}{15}$

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AM radio frequencies range between 550 kHz (kilohertz) and 1600 kHz and travel at the same speed, 3.0 x 108 m/s. What is the wav

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Explanation:

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The most precise method for determining the actual temperature of vaccines is to use a buffered temperature probe.

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Hence, the use of a buffered temperature probe is the most accurate way to measure actual vaccine temperatures.

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2 years ago

A father racing his son has half the kinetic energy of the son, who has half the mass of the father.The father speeds up by 1.0

Helga [31]

Answer:

(a) $v_f=2.414\ m.s^{-1}$

(b) $v_s=4.828\ m.s^{-1}$

Explanation:

Let:

mass of father be, $m_f$

mass of son be, $m_s=\frac{m_f}{2}$

speed of son be, $v_s$

initial speed of father be, $v_f$

After speeding up, speed of father is $v_f+1$

<u>We know Kinetic Energy is given as</u>

$KE=\frac{1}{2} m.v^2$ .....................................(1)

where:

m = mass

v = velocity

Hence, according to the initial condition the father is having kinetic energy half the kinetic energy of the son.

$KE_s=2.KE_f$

$\frac{1}{2} m_s.v_s^2=2\times \frac{1}{2} m_f.v_f^2$

$(\frac{m_f}{2})\times v_s^2=2\times m_f\times v_f^2$

$v_s=2v_f$ .................................................(2)

According to the final condition:

$\frac{1}{2} m_s.v_s^2= \frac{1}{2} m_f.(v_f+1)^2$

$(\frac{m_f}{2})\times v_s^2=m_f.(v_f+1)^2$

$v_s^2=2(v_f+1)^2$

$v_s=\sqrt{2}(v_f+1)$ .....................................................(3)

(a)

From eq. 2 & 3

$2v_f=\sqrt{2}(v_f+1)$

$\sqrt{2}\ v_f=(v_f+1)$

$v_f(\sqrt{2}-1)=1$

$v_f=\frac{1}{(\sqrt{2}-1)}$

$v_f=2.414\ m.s^{-1}$

(b)

<em>putting the above value in eq. (2)</em>

$v_s=4.828\ m.s^{-1}$

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4 years ago