PHYSICAL SCIENCES (PHYSICS) GRADE 12 PDF:ELECTRICITY
QUESTION 1
A learner wants to use a battery with an emf of 13 V to operate a walking doll. The battery has an unknown internal resistance of r. The walking doll has a resistance of 6 Ω. The learner uses the circuit below to obtain the potential difference required for the walking doll to function. When switch S is closed, the reading on the voltmeter drops to 12 V and the walking doll functions at its maximum power of 6 W.
1.1 Explain briefly why the reading on the voltmeter drops when switch S is closed. (2)
1.2 Calculate the internal resistance, r, of the battery. Show all the steps in your calculations.(9)
1.3 Calculate the magnitude of the unknown resistor, R.(3)
1.4 The resistor R is replaced with a conducting wire of negligible resistance. What effect will this have on the “lost volts”? Fully explain your answer.(4) [18]
QUESTION 1
A learner wants to use a battery with an emf of 13 V to operate a walking doll. The battery has an unknown internal resistance of r. The walking doll has a resistance of 6 Ω. The learner uses the circuit below to obtain the potential difference required for the walking doll to function. When switch S is closed, the reading on the voltmeter drops to 12 V and the walking doll functions at its maximum power of 6 W.
1.1 Explain briefly why the reading on the voltmeter drops when switch S is closed. (2)
1.2 Calculate the internal resistance, r, of the battery. Show all the steps in your calculations.(9)
1.3 Calculate the magnitude of the unknown resistor, R.(3)
1.4 The resistor R is replaced with a conducting wire of negligible resistance. What effect will this have on the “lost volts”? Fully explain your answer.(4) [18]