The correct answer to the question is : 9375 N.
CALCULATION:
As per the question, the mass of the car m = 1500 Kg.
The diametre of the circular track D = 200 m.
Hence, the radius of the circular path R = 
= 
= 100 m.
The velocity of the truck v = 25 m/s.
When a body moves in a circular path, the body needs a centripetal force which helps the body stick to the orbit. It acts along the radius and towards the centre.
Hence, the force acting on the car is centripetal force.
The magnitude of the centripetal force is calculated as -
Force F = 
= 
= 9375 N. [ANS}
The centripetal force is provided to the car in two ways. It is the friction which provides the necessary centripetal force. Sometimes friction is not sufficient. At that time, the road is banked to some extent which provides the necessary centripetal force.
A) d. 10T
When a charged particle moves at right angle to a uniform magnetic field, it experiences a force whose magnitude os given by

where q is the charge of the particle, v is the velocity, B is the strength of the magnetic field.
This force acts as a centripetal force, keeping the particle in a circular motion - so we can write

which can be rewritten as

The velocity can be rewritten as the ratio between the lenght of the circumference and the period of revolution (T):

So, we get:

We see that this the period of revolution is directly proportional to the mass of the particle: therefore, if the second particle is 10 times as massive, then its period will be 10 times longer.
B) 
The frequency of revolution of a particle in uniform circular motion is

where
f is the frequency
T is the period
We see that the frequency is inversely proportional to the period. Therefore, if the period of the more massive particle is 10 times that of the smaller particle:
T' = 10 T
Then its frequency of revolution will be:

Answer:
we conclude that visible light is that electromagnetic wave that makes up the colors of a rainbow seen after a storm.
Hence, option A is correct.
Explanation:
Generally, after the storm, we can witness the presence of a rainbow with our naked eyes. Rainbow, visible to our eyes, consists of all the seven constituent colors of white light. Those seven colors range from violet to red, all having different wavelengths. When water particles present in our atmosphere get exposed to light, all the constituent colors of a white light tend to deviate at a variety of angles. It happens due to their refraction through water particles; thus, a spectrum is obtained.
As we cannot see X-rays, UV rays, and infrared waves through our naked eye, visible light is the kind of electromagnetic wave that makes anyone able to see the objects.
Please note that all the constitute colors of a beautiful rainbow associate with the visible region of the electromagnetic spectrum.
Therefore, we conclude that visible light is that electromagnetic wave that makes up the colors of a rainbow seen after a storm.
Hence, option A is correct.
Answer:
Number of photons travel through pin hole=
Explanation:
First we will calculate the energy of single photon using below formula:

Where :
h is plank's constant with value 
c is the speed of light whch is
λ is the wave length = 532nm

E=
J
Number of photons emitted per second:

Number of photons emitted per second=
=
Where:
A-hole is area of hole
A-beam is area of beam
d-hole is diameter of hole
d-beam is diameter if beam
=
=
=
Number of photons travel through pin hole=
Number of photons travel through pin hole=