Answer:
It is also called law of Malus,the law states that the intensity of a beam of plane-polarized light after passing through a rotatable polarizer varies as square of the cosine of the angle through which the polarizer is rotated from the position that gives maximum intensity expand.
Before u can know it u have to understand it, so go through it over and over again and u will get it.
Corrected question: The wavelength of light beam<u> </u><u>A</u> is twice the wavelength of light beam B. The energy of a photon in beam A is:
Answer:
B
Explanation:
Energy = hc/λ
λ(A) =2λ(B)...................equation 1
We will solve for the ratio of energy of A to energy of B.which is
=(hc/λA) ÷ (hc/λB)
referring to equation 1 we have
=(hc/2λB) ÷ (hc/λB)
=hc/2λB) × (λB/hc)
= λB/2λB
=1/2
The energy of A is half of B
Answer:
13.78 m/s
Explanation:
Given that:
The mass of the girl & her bicycle = 42 kg
The speed at the top of the hilll= 4 m/s
The height of the hill = 14.3 m
The length of the hill (distance) = 112 m
The frictional force = 20 N
To find the speed at the bottom of the hill; we need to carry out the following processes.
The workdone by gravity = mass × acceleration due to gravity × Δh
= 42 × 9.8 × ( 14.3 - 0 )
= 5885.88 joules
The workdone by the friction = Force × distance = - 20 × 112 (since she is riding down the hill)
The workdone by the friction = -2240 Joules
The initial Kinetic friction = 1/2 mv²
= 1/2 × 42 × 4²
= 336 Joules
The final kinetic energy = Initial Kinetic energy + total work
The final kinetic energy = (336 + 5885.88 - 2240) Joules
The final kinetic energy = 3981.88 Joules
Using the final kinetic energy = 1/2 mv²
3981.88 = 1/2 × 42 × v²
3981.88 = 21 v²
v² = 3981.88/21
v² =189.61
v =
v = 13.78 m/s
Therefore, the speed at the bottom = 13.78 m/s