The wavelength and frequency of light are closely related. The higher the frequency, the shorter the wavelength. Because all light waves move through a vacuum at the same speed, the number of wave crests passing by a given point in one second depends on the wavelength. That number, also known as the frequency, will be larger for a short-wavelength wave than for a long-wavelength wave.
Given :
An electron moving in the positive x direction experiences a magnetic force in the positive z direction.
To Find :
The direction of the magnetic field.
Solution :
We know, force is given by :

Here, q = -e.

Now, for above condition to satisfy :

So, 
Therefore, direction of magnetic field is negative y direction.
Hence, this is the required solution.
Since the bulb consumes 100 watts of power and its efficiency is 95%,
it generates 95 watts of light energy and 5 watts of heat energy whenever
it's turned on.
5 watts means 5 joules of energy per second.
(2.5 hours) x (3,600 seconds/hour) = 9,000 seconds
(9,000 seconds) x (5 joules/second) = 45,000 joules of heat in 2.5 hours
Explanation:
Displacement is the straight line distance from the starting position to the final position.
Person X walks halfway around circle. So her displacement is 100 m.
Person Y walks 3/4 of the way around. So his displacement is 50√2 m ≈ 70.7 m.
Person Z walks completely around the circle, so their displacement is 0 m.
Therefore:
Z < Y < X
I haven't worked on Part-A, and I don't happen to know the magnitude of the gravitational force that the Sun exerts on the Earth.
But whatever it is, it's exactly, precisely, identical, the same, and equal to the magnitude of the gravitational force that the Earth exerts on the Sun.
I think that's the THIRD choice here, but I'm not sure of that either.