Answer:
Magnetic field, B = 
(eastwards)
Explanation:
Given that,
The magnitude of electric field, E = 3.7 V/m
A plane electromagnetic wave travels northward. We need to find the magnitude and direction of the magnetic field at this instant.
The relation between the magnetic field and the electric field of the plane electromagnetic wave is given by :
c is the speed of light
So, the magnetic field is . The direction of magnetic field is perpendicular to the electric field and the direction of wave propagation. Hence, the direction of magnetic field is eastward.
Options (b) and (d) are correct about an electric motor.
An electric motor is a device which coverts electrical energy into mechanical energy.It works on the principle that when a current carrying coil is placed in a magnetic field, it experiences torque. Because of that torque, the coil rotates and thus the electrical energy gets converted into mechanical (motion) energy.
An inclined plane decreases the amount of force needed to move an object but increases the distance the onject needs to be moved. Since work = distance x force, whe amount of work stays the same.
Explanation:
It is given that,
The period of the carrier wave, T = 0.01 s
Let f and 
are frequency and the wavelength of the wave respectively. The relationship between the time period and the frequency is given by :
f = 100 Hz
The wavelength of a wave is given by :
So, the frequency and wavelength of the carrier wave are 100 Hz and 
respectively. Hence, the correct option is (c).
