Answer
Verified
397.8k+ views
Hint: In order to solve this question, we will use the concept that whenever a plane mirror rotates to an angle say $\theta $ then the light ray which is reflected from the plane mirror will rotate through an angle of $2\theta $ and hence will make double rotations as compared with rotations of plane mirror.
Complete answer:
As, it’s given that the plane mirror rotates with the number of revolutions in one second is $12$ .
So, the number of revolutions made by reflected rays from the plane mirror will be twice of twelve which is $24$ .
Also, this number of revolutions per second is also called the frequency of the body so, $f = 24$
Speed of the reflected light can be calculated by:
$v = 2\pi R \times f$
Where, $R = 1.5m$ which is the radius of the sphere.
So,
$v = 2\pi \times 1.5 \times 24$
$v = 72\pi m{\sec ^{ - 1}}$
Hence, the speed of the light spot on the surface is given by $v = 72\pi m{\sec ^{ - 1}}$ .
Note: It must be remembered that, whenever a plane mirror is rotated with some angle say $\theta $ then the reflected ray of light will always rotate with an angle of $2\theta $ and the revolutions per second is the frequency of a body in $radians{\sec ^{ - 1}}$ , which also have a unit denoted as $Hertz$ written as $Hz$.
Complete answer:
As, it’s given that the plane mirror rotates with the number of revolutions in one second is $12$ .
So, the number of revolutions made by reflected rays from the plane mirror will be twice of twelve which is $24$ .
Also, this number of revolutions per second is also called the frequency of the body so, $f = 24$
Speed of the reflected light can be calculated by:
$v = 2\pi R \times f$
Where, $R = 1.5m$ which is the radius of the sphere.
So,
$v = 2\pi \times 1.5 \times 24$
$v = 72\pi m{\sec ^{ - 1}}$
Hence, the speed of the light spot on the surface is given by $v = 72\pi m{\sec ^{ - 1}}$ .
Note: It must be remembered that, whenever a plane mirror is rotated with some angle say $\theta $ then the reflected ray of light will always rotate with an angle of $2\theta $ and the revolutions per second is the frequency of a body in $radians{\sec ^{ - 1}}$ , which also have a unit denoted as $Hertz$ written as $Hz$.
Recently Updated Pages
A ray of light passes through an equilateral prism class 12 physics JEE_Main
The size of the image of an object which is at infinity class 12 physics JEE_Main
When a glass slab is placed on a cross made on a sheet class 12 physics JEE_Main
Rays from Sun converge at a point 15 cm in front of class 12 physics JEE_Main
For the circuit shown in figure the equivalent capacitance class 12 physics JEE_Main
If on applying the potential of 20 V on a conductor class 12 physics JEE_Main
Trending doubts
Which are the Top 10 Largest Countries of the World?
What is the definite integral of zero a constant b class 12 maths CBSE
Differentiate between homogeneous and heterogeneous class 12 chemistry CBSE
What are the major means of transport Explain each class 12 social science CBSE
Explain sex determination in humans with the help of class 12 biology CBSE
How much time does it take to bleed after eating p class 12 biology CBSE