2nd Year Physics Chapter 19 Exercise Solved Questions

Hello dear FSC students, I hope you all are doing great. In today’s tutorial, we will have a look at 2nd Year Physics Chapter 19 Solved Questions. I have started a series of tutorials related to the solution of questions given in 2nd-year physics. In the previous tutorial, I have discussed all the questions of chapter18 with the detailed.

In this post, we will have a detailed look at all the questions given in chapter 19 of FSC physics. I will explain all the questions one by one and give an answer to every question in a simple way. So let’s get started with 2nd Year Physics Chapter 19 Exercise Solved Questions

2nd Year Physics Chapter 19 Exercise Solved Questions

• So friends discuss all these questions one by one with the detailed.

Question 19.1

• The measurements on which relative motion always agree upon are.
• Speed of light in space.
• The force applying on moving bodies.

Question 19.2

• The special theory of relativity says time is not an absolute quantity. It depends on the motion of the frame of reference.
• The information of science relies on observation and calculations. So time passes slowly or dilate.

Question 19.3

(a):

• If you are moving in a spaceship with high speed there will be no pulse variation due to the absence of relative motion.

(b):

• As the speed of the spaceship is larger than the earth due to that pulse rate of people in the spaceship will be high as compared to people on the earth.

Question 19.4

• If the speed of light is infinity then we have.

m = m, l = l, t = t , c = ∞.
m= (m_o) /(√1 – v2 /∞) = m_o / (√1– 0) =m_o.
l= l_o (√ 1 – v2 /∞) = l_o (√ 1 – 0)=l_o.
t = t_o / (√ 1 – v2 /∞)  = t_o / (√ 1 – 0) =t_o.
E = m(∞)Square ⇒ ‘E’ is infinity.

Question 19.5

• The work done for compression of spring will be transformed into energy.
• As we are familiar with the Einstein energy equation.

E=mc²

• So with the increment in energy mass will also increase.

Question 19.6

• The types of emitted radiation from the hot body depend on the temperature of body.
• At less temperature emitted radiation has a larger wavelength. The larger wavelength in the visible region is of RED color so it appears first.

Question 19.7

• According to Stepan Boltzmann law energy radiated per second per square meter is given as.

E = σT⁴

• If the value of temperature is doubled or T’=2T
• Then we have.

E’ = σ(2T)⁴

E’ = 16σT⁴

E’=16E

Question 19.8

• As we known the formula for the energy of photons is given as.

E=hf=hc/λ since V=fλ

• The energy of photon is.

E=n(hc/λ)

n=Eλ/hc

• The parameters E, h and c are constant so.

n∝λ

• From this, you can see that photons for red beam are large due to a larger wavelength.

Question 19.9

• As we know that.

E=hc/λ

p=h/λ

• As the wavelength of blue light is less due that it has large energy and momentum.

Question 19.10

• The formula for energy quanta is given here.

E=hc/λ

• As the wavelength of a radio wave is larger than the X-rays so from above equation it has less energy quanta.

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