Q.No.13.8: - Explain why the terminal potential of a battery decreases when the current drawn from it is increased?

Q.No.13.8: - Explain why the terminal potential of a battery decreases when the current drawn from it is increased?

Ans: - The terminal potential difference of a batter is

                                        IR      =        E – I.r

                                        V_t       =        E – I.r

Where,  E is the emf of the battery, r is the internal resistance of battery, and I.r is the potential difference across internal resistance.

When I increased then I.r becomes larger and terminal potential becomes small. Thus, we can say that when we draw more current from battery then its terminal potential difference will decrease.

Here is a rough example for this concept. The example of current flow is just like a water flow. Let suppose the pressure of water is just like the potential in the electrical system. The dam have a large capacity of water and suppose you are drawing more and more water from the dam and as a result water in the dam becomes low level and now it has low pressure on water to flow. Similarly when we draw more current from the battery then the terminal potential of the battery decreases just like dam pressure on water flow. I just tried to make this answer clear this is not a fit example for it but in my view you can understand something from it.

Q.No.13.7: - Describe a circuit which will give a continuously varying potential?

Q.No.13.7: - Describe a circuit which will give a continuously varying potential?

Ans: - A potential divider or potentiometer is a circuit which can give a continuously varying potential. Consider a resistance R in the form of a wire on which a terminal C can slide. The resistance between A and C can be varied from 0 to R, as C slides from A to B.

          If we connect a battery of emf E across a resistance R. The current flowing thought it is

                                                  I        =        E/R

If we represent the resistance between A and C by r, the potential drop between these points will be

                                                  V        =        rI

Now,

                                                  V        =        r x E/R

Thus as C slides from A to B, r varies from 0 to R, and the potential drop between A and C changes from zero to E. This arrangement by which potential can be varied continuously from 0 to E is known as a potential divider.   (Sorry for Diagram. Pleas concert with Text Book for diagram.)

Q.No.12.9: - Do electrons tend to go to region of high potential or of low potential.

Q.No.12.9: - Do electrons tend to go to region of high potential or of low potential.

Ans: - By convention we use positive potential as a high and negative potential as low potential. So according to this convention we can say that electrons which have negative charge tend to go to the region of high potential (positive) from low potential (negative).

Q.No.12.2: - Suppose that you follow an electric field line due to a positive point charge. Do electric field and the potential increase or decrease?

Q.No.12.2: - Suppose that you follow an electric field line due to a positive point charge. Do electric field and the potential increase or decrease?

Ans: - If we follow an electric field line due to a positive point charge then we will move away from the positive point charge because the electric field produced by a positive charge is away from charge. Electric field and electric potential both inversely dependent on the distance from the charge to the selected point (say P). So as we follow the positive charge then we will move away from the charge. The formula of electric field  and electric potential is

                    E    =    qq′/4πЄ₀r²      and       V     =     q/4πЄ₀r    

So as we follow then electric field and electric potential will decrease.

Q.No.12.1: - The potential is constant throughout a given region of space. Is the electrical field zero or nonzero in this region? Explain.

Q.No.12.1: - The potential is constant throughout a given region of space. Is the electrical field zero or nonzero in this region? Explain.

Ans: - The electric field has a relation with change in electrical potential which is

                                                E   =   -ΔV/Δr

In this case ΔV is the change in electrical potential and if the change in potential is zero then E will be zero and ΔV will be zero only when there is no change in electrical potential. This is given in question that electrical potential is constant throughout the given region of space hence, E = 0 when ΔV=0

Mathematically,

                                  E   =   -ΔV/Δr   =    -0/Δr    =   0