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Current Electricity · Question 43

NEET 2018MCQEasy📈 Topic in 0% papers+4−1
1

A battery consists of a variable number n of identical cells (having internal resistance r each) which are connected in series. The terminals of the battery are short-circuited and the current I is measured. Which of the graphs shows the correct relationship between I and n?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]

Answer

(1) [figure]

Solution

For n identical cells (emf E each) in series: total emf = nE, total internal resistance = nr

Terminals short-circuited ⇒ external resistance = 0

⇒ I = nEnr = Er

∴ I is independent of n ⇒ the graph is a straight line parallel to the n-axis.

Answer: (1)

NEET 2018

Keep practising — Current Electricity

2

A carbon resistor of (47 4.7) k is to be marked with rings of different colours for its identification. The colour code sequence will be

  1. Violet – Yellow – Orange – Silver
  2. Yellow – Violet – Orange – Silver
  3. Yellow – Green – Violet – Gold
  4. Green – Orange – Violet – Gold
NEET 2018
3

The resistance of a wire is 'R' ohm. If it is melted and stretched to 'n' times its original length, its new resistance will be

  1. Rn
  2. n2R
  3. Rn2
  4. nR
NEET 2017
4

A potentiometer is an accurate and versatile device to make electrical measurements of EMF because the method involves

  1. potential gradients
  2. a condition of no current flow through the galvanometer
  3. a combination of cells, galvanometer and resistances
  4. cells
NEET 2017
5

A potentiometer wire is 100 cm long and a constant potential difference is maintained across it. Two cells are connected in series first to support one another and then in opposite direction. The balance points are obtained at 50 cm and 10 cm from the positive end of the wire in the two cases. The ratio of emf's is

  1. 3 : 4
  2. 3 : 2
  3. 5 : 1
  4. 5 : 4
NEET 2016 (Phase 1)
6

The charge flowing through a resistance R varies with time t as Q = at - bt2, where a and b are positive constants. The total heat produced in R is

  1. a3R2b
  2. a3Rb
  3. a3R6b
  4. a3R3b
NEET 2016 (Phase 1)
7

The potential difference (VA - VB) between the points A and B in the given figure is [figure]

  1. -3 V
  2. +3 V
  3. +6 V
  4. +9 V
NEET 2016 (Phase 2)
8

A filament bulb (500 W, 100 V) is to be used in a 230 V main supply. When a resistance R is connected in series, it works perfectly and the bulb consumes 500 W. The value of R is

  1. 230
  2. 46
  3. 26
  4. 13
NEET 2016 (Phase 2)
9

Two metal wires of identical dimensions are connected in series. If 1 and 2 are their conductivities, the effective conductivity of the combination is

  1. 1 + 2 1 2
  2. 1 2 1 + 2
  3. 2 1 2 1 + 2
  4. 1 + 22 1 2
AIPMT 2015
10

A potentiometer wire of length L and a resistance r are connected in series with a battery of e.m.f. E0 and a resistance r1. An unknown e.m.f. E is balanced at a length l of the potentiometer wire. The e.m.f. E will be given by

  1. E0lL
  2. LE0r(r + r1)l
  3. LE0rlr1
  4. E0r(r + r1) lL
AIPMT 2015
11

A, B and C are voltmeters of resistance R, 1.5R and 3R respectively as shown in the figure. When some potential difference is applied between X and Y, the voltmeter readings are VA, VB and VC respectively, Then [figure]

  1. VA = VB VC
  2. VA VB VC
  3. VA = VB = VC
  4. VA VB = VC
AIPMT 2015 (Cancelled)

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