# Quizzes : Current Electricity

QUIZ TEST-II

Question:21. A circuit consists of a resistance R connected to n similar cells. If the current in the circuit is the same whether the cells are connected in series or in parallel then the internal resistance r of each cell is given by

(A) r = R/n

(B) r = nR

(C) r = R

(D) r = 1/R

Click to See Answer :
Ans: (C)

Question:22. A cell of e.m.f. E and internal resistance r is connected in series with an external resistance nr then the ratio of the terminal potential difference to E.M.F. is

(A) 1/n

(B) 1/n+1

(C) n/n+1

(D) n+1/n

Click to See Answer :
Ans: (C)

Question:23. To measure a potential difference across a resistor of resistance R Ω a voltmeter of resistance Rvis used. To measure the potential with a minimum accuracy of 95 % then

(A) Rv = 5R

(B) Rv = 15 R

(C) Rv = 10 R

(D) Rv ≥ 19 R

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Ans: (D)

Question:24. A cell of E.M.F. E and internal resistance r supplies currents for the same time t through external resistance R1 and R2 respectively. If the heat produced in both cases is the same then the internal resistance is

(A) 1/r = 1/R1 + 1/R2

(B) r = (R1 + R2)/2

(C) r = √(R1 R2)

(D) r = R1 + R2

Click to See Answer :
Ans: (C)

Question:25. A battery of 10 volt is connected to a resistance of 20 ohm through a variable resistance R, the amount of charge which has passed in the circuit in 4 minutes, if the variable resistance R is increased at the rate of 5 ohm/min.

(A) 120 coulomb

(B) 120 loge2 coulomb

(C) 120/loge2 coulomb

(D) 60/loge2 coulomb

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Ans: (B)

Question:26. ABCD is a square of side ‘a’ metres and is made of wires of resistance x ohms/metre. Similar wires are connected across the diagonals AC & BD. The effective resistance between the corners A & C will be

(A) (2 – √2) ax

(B) 6ax

(C) 3ax

(D) (3 – √2) ax

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Ans: (A)

Question:27. To get maximum current in a resistance of 3 Ω , one can use n rows of m cells (connected in series) connected in parallel. If the total no. of cells is 24 and the internal resistance is 0.5 ohm then

(A) m = 12, n = 2

(B) m = 8, n = 3

(C) m = 2, n = 12

(D) m = 6, n = 4

Click to See Answer :
Ans: (A)

Question:28. In the circuit below the resistance R has a value that depends on the current. Specifically, R is 20 ohms when I is zero and the increase in resistance in ohms is numerically equal to one half of the current in amperes. What is the value of current I in circuit ?

(A) 8.33 amp

(B) 10 amp

(C) 12.5 amp

(D) 18.5 amp

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Ans: (B)

Question:29. The potential difference between points A & B in a section of a circuit shown is

(A) 5 volts

(B) 1 volts

(C) zero volts

(D) 13 volts

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Ans: (D)

Question:30. Two cells of the same e.m.f. e but different internal resistances r1 and r2 are connected in series with an external resistance ‘R’. the potential drop across the first cell is found to be zero. The external resistance R is

(A) r1 – r2

(B) r1 / r2

(C) r1 r2

(D) r1 + r2

Click to See Answer :
Ans: (A)

Click to See All Answers :
21. C   22. C   23. D   24. C   25. B   26. A   27. A   28. B   29. D   30. A

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