The n rows each containing m cells in series are joined in parallel. Maximum current is taken from this combination across an external resistance of 3 Ω. If the total number of cells used is 24 and internal resistance of each cell is 0.5 Ω, then

1.  m = 8, n = 3

2.  m = 6, n = 4

3.  m = 12, n = 2

4.  m = 2, n = 12

Subtopic: Grouping of Cells |

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Q34:

If the intensities of the two interfering beams in Young’s double-slit experiment are

and

then the contrast between the maximum and minimum intensities are good when

1.

Subtopic: Young's Double Slit Experiment |

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Q35:

A simple telescope, consisting of an objective of focal length 60 cm and a single eye lens of focal length 5 cm is focused on a distant object in such a way that parallel rays emerge from the eye lens. If the object makes an angle of 2 º at the objective, then the angular width of the image is

1. 10 º

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Q36:

A semiconductor has an electron concentration of per and a hole concentration of per . The electron mobility is 25000 and the hole mobility is 100 . Then,

1. the semiconductor is n-type

2. the conductivity is 320 m mho

3. Both (a) and (b)

4. None of the above

Subtopic: Types of Semiconductors |

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Q37:

An ammeter and a voltmeter are joined in series to a cell. Their readings are A and V respectively. A resistance is now joined in parallel with the voltmeter. Then,

1. Both A and V will increase

2. Both A and V will decrease

3. A will decrease, V will increase

4. A will increase, V will decrease

Subtopic: Grouping of Cells |

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Q38:

Three identical capacitors A, B and C are charged to the same potential and then made to discharge through three resistance . Their potential differences (V) are plotted against time t, giving the curves 1, 2 and 3. Choose the incorrect option.

1.

2.

3.

4. None of the above.

Subtopic: Capacitance |

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Q39:

The diffraction pattern of a single slit consists of a central bright band which is:

1.	wide, and is flanked by alternate dark and bright bands of decreasing intensity
2.	narrow, and is flanked by alternate dark and bright bands of equal intensity
3.	wide, and is flanked by alternate dark and bright bands of equal intensity
4.	narrow and is flanked by alternate dark and bright bands of decreasing intensity

Subtopic: Diffraction |

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Q40:

The logic circuit as shown below has the input waveforms A and B as shown. Pick out the correct output waveform.

1.

2.

3.

4.

Subtopic: Logic gates |

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Q41:

Direction: In each of the following questions, a Statement of assertion is given followed by a corresponding Statement of reason.

Assertion (A) Linear momentum of a body changes even when it is moving uniformly in a circle.
Reason (R) In uniform circular motion velocity remains constant.

1. Both assertion and reason are true and reason is the correct explanation of assertion.

2. Both assertion and reason are true but reason is not the correct explanation of assertion.

3. Assertion is true but reason is false.

4. Both assertion and reason are false.