Electric Potential and Potential Difference - UNSOLVED PRACTICE SET

Q7. Define electric potential difference. Write its formula and SI unit. What does a potential difference of 5 V between two points mean physically?   

Q8. Define 1 volt in terms of work done and charge. Write the formula V = W/Q and explain each symbol.

Q9. How is a voltmeter connected in a circuit? What must be the ideal resistance of a voltmeter and why?

Q10. A battery of EMF 9 V is connected to a circuit. The terminal voltage measured is 8.4 V.
(a) What is the potential drop across the internal resistance?
(b) What causes this drop?

Q11. Explain the analogy between water flow in a pipe and electric current in a wire. What corresponds to potential difference in the water analogy? 

Q12. Why does current flow from higher potential to lower potential? What would happen if both ends of a wire were at the same potential?

Q13. Explain the concept of electric potential and potential difference in detail. Your answer must cover:
(a) what electric potential means at a single point (work done per unit charge to bring a positive charge from infinity to that point),
(b) the definition and formula of potential difference (V = W/Q),
(c) the SI unit (volt) and the definition of 1 V,
(d) how a battery maintains a potential difference between its terminals, and
(e) why charge flows only when there is a potential difference — connect this to the water-flow analogy.

Q14. A 12 V car battery is connected to the headlight circuit of a Maruti Suzuki. The headlight draws 3 A of current.
(a) Calculate the work done by the battery in driving this current for 10 minutes.
(b) If the internal resistance of the battery is 0.2 Ω, calculate the terminal voltage.
(c) How much of the battery's energy is 'lost' across the internal resistance per second?
(d) Explain what happens to the terminal voltage when the current demand increases (e.g. starting the car engine).
(e) Define EMF and explain how it differs from terminal voltage.

Q15. Explain how a voltmeter and ammeter work together in a circuit to measure potential difference and current.
(a) Describe the connection of each instrument in the circuit (series/parallel).
(b) Explain why a voltmeter must have very high resistance and an ammeter very low resistance.
(c) What errors arise if these conditions are not met?
(d) Draw (or describe) a circuit with a resistor, showing correct positions for both instruments.
(e) Why is the potential difference across an open switch equal to the EMF of the battery?

Q16. A charge of 8 C moves through a potential difference of 15 V. 

(a) Calculate the work done.

(b) If this work was done in 4 seconds, calculate the power.
(c) Calculate the current flowing.
(d) What is the resistance in the circuit?

Q17. A battery has an EMF of 6 V and internal resistance 0.5 Ω. It is connected to an external resistance of 5.5 Ω.
(a) Calculate the current in the circuit.
(b) Calculate the terminal voltage of the battery.
(c) Calculate the work done by the battery in 2 minutes.
(d) Calculate the energy dissipated in the internal resistance per minute.

Q18. In a household circuit in Chennai, 180 J of work is done in moving 15 C of charge through a cooler.
(a) Calculate the potential difference across the cooler.
(b) If the cooler operates for 30 minutes, find the total charge that passes through.
(c) Find the total work done in 30 minutes.
(d) If the mains voltage is 220 V but the cooler operates at only 12 V, explain how a transformer achieves this.