The electromotive force (∈) = 2 V
<h3>Further explanation</h3>
Given
I=2 A
t = 30 s
E = 120 J
Required
The electromotive force (∈)
Solution
The electromotive force : the potential difference between two electrodes in galvanic cell
Can be formulated :

E = energy, J
Q = charge , Coulomb = i.t

"An object in motion stays in motion, and an object at rest remains at rest unless acted upon by an unbalanced force" Said Sir Isaac Newton
Hope that helped! :)
Amplitude is a measure of the size of sound waves. It depends on the amount of energy that started the waves. Greater amplitude waves have more energy and greater intensity, so they sound louder. ... The same amount of energy is spread over a greater area, so the intensity and loudness of the sound is less.
Answer with Explanation:
Electric field:It is the force per unit charge experienced by rest charge at any given point.
It is the area around the charge which is placed at rest.It is represented by E.
Mathematical formula:

Magnetic field:It is an area around moving charge in which moving charge particle experienced magnetic force in that area.
Magnetic field is represented by B.
Mathematical formula :

Where B=Magnetic field
q=Charge on particle
v=Velocity of particle
F=Magnetic force exert on particle
Answer:
Store chemical energy and transfer it to electrical energy when a circuit is connected.
Explanation:
A battery (single cell) is a container made of one cell that can produce a particular amount of electrical energy when needed.
It works by converting chemical energy to electric energy which is then used as a power source.
It stores up chemical energy and when connected to an external circuit, it provides electrical energy (through the flow of electrical current) to the circuit.
A battery is usually made up of a positive electrode and a negative electrode.