I think its all four of them could be wrong but try all four !!!!!!
I hope the wire is not wound too tightly around the bar magnet.
The device will generate electrical energy when the bar magnet
is moving in or out of the coil of wire.
Answer:

Explanation:
A polarizer changes the orientation of the oscillations of a light wave.
I₀ = Intensity of unpolarized light = 10
θ = Angle given to the polarizer = 60°
Intensity of light
I = I₀cos²θ
⇒I = 10cos²60

So, the after passing through the second polarizer is 
Beta emission is occurring in the given nuclear reaction.
Answer: Option B
<u>Explanation:</u>
In this equation, the reactant is the Thorium atom, which is reduced to palladium. As the atomic number get decreased by one, so an electron will be emitted. This process of emission of electrons by radiation or decaying the reactant nuclei to form a new product nuclei is termed as beta emission.
So, the electrons are generally termed as beta particles while the positrons are termed as positive beta particles. So this is a kind of radioactive reactions where the reactant changes to new element by releasing an electron and thus there is a change in the atomic number of the product by one.