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

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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

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Ans: (C)

 

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

(A) R_v = 5R

(B) R_v = 15 R

(C) R_v = 10 R

(D) R_v ≥ 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

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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 log_e2 coulomb

(C) 120/log_e2 coulomb

(D) 60/log_e2 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

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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

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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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