For accurate measurements, the resistance of a voltmeter should be

- infinite
- as small as possible
- as large a possible
- equal to the resistance across which potential difference is to be measured

Consider the circuit given below

The rate at which energy is dissipated is 20Ω resistor

(a) 14.2 Watt

(b) 8.97 Watt

(c) 97.7 Watt

(d) 47.2 Watt

Current through 10Ω resistor is

- 1.54 A
- 0.67 A
- 1.22 A
- 2.21 A

Power of battery having emf E

- 44.2 Watt
- 30.8 Watt
- 13.4 Watt
- 20 Watt

Consider the figure given below

If ammeter shows a reading of 10A and voltmeter having internal resistance 3000 Ω measures a voltage of 200V, the resistance R is given by

- 201.3 Ω
- 2013 Ω
- 20.13 Ω
- 20.00 Ω

A constant voltage is applied between the two ends of a uniform metallic wire. Some heat is developed in it. The heat developed is doubled if

(a) both length and radius of wire are halved

(b) both length and radius of wire are doubled

(c) the radius of wire id doubled

(d) length of wire is doubled

Solution

If a wire of resistance 2Ω is covered with ice and a voltage of 210V is applied across the wire , then rate of melting ice would be

- 0.85g/s
- 1.92g/s
- 6.56g/s
- none of the above

Which of the following statements is/are correct?

- Both Peltier and Joule effects are reversible
- Both Peltier and Joule effects are irreversible
- Joule effect is reversible and Peltier effect is irreversible
- Joule effect is irreversible and Peltier effect is reversible

The arrangement shown below is of the meter bridge experiment. Here AC=x corresponds to the null deflection in the galvanometer. What will be the value of AC if the radius of the wire AB is doubled?

- x/2
- x/4
- 2x
- x

- Both assertion and reason are true and reason is correct explanation of assertion
- Both assertion and reason are true and reason is not the correct explanation of assertion
- Assertion is true but reason is false
- Both assertion and reason are false.

The distribution of currents within the network for a given amount of current always takes place in a way that leads to minimum total power distribution in the circuit

For maximum output current by a source the source resistance must be equal to external load resistance.

When temperature of a cold junction of a thermocouple is lowered , the value of neutral temperature of this thermocouple rises

More thermo emf is produced when temperature difference between two junctions of thermocouple is raised.

A domestic appliance, working on a three pin , will continue working even if the top pin is removed

Third pin is used as a safety device.

A potentiometer of larger length is used for accurate measurements

Potential gradient for potentiometer of larger length with a given battery becomes small.

Solution 10-13

12 wires each of resistance RΩ are connected in the form of a skeleton cube as shown below in the figure

If current I enter at point A and leaves at diagonally opposite point G then the equivalent resistance of the cube would be

(a)12R/5

(b)12R

(c) 6R/5

(d) 5R/6

Solution

Here AB is a wire of total resistance R

Current through ideal ammeter for any 0<p<1 is

Solution

Value of p for which ammeter reads maximum value is

(a) 0

(b) 1

(c) 2

(d) 3

Solution

(C) Consider the circuit given below

Total resistance in the circuit is

(a) 5Ω

(b) 6Ω

(c) (11/6)Ω

(d) 3Ω

Solution

Current in the circuit is

(a) 4A

(b) 12A

(c) 6A

(d) 2A

Solution

Potential difference between points A and E is

(a) 12V

(b) 6V

(c) 10V

(d) 5V

Solution

Potential at point E is

(a) 10 V above the ground

(b) 10 V below the ground

(c) 2 V above the ground

(d) 2 V below the ground

Solution

Power supplied by the battery is

(a) 12 W

(b) 10W

(c)22W

(d)24W

Solution

Consider the two circuits given below

Column A |
Column B |

(P) Point of lowest potential in circuit A has its value equal to |
(U) 0.15 A |

(Q) Circuit current in circuit B is |
(V) 4V |

(R) Circuit current in circuit A is |
(W) 15V |

(S) Potential of point B in circuit B is |
(X) 90V |

(T) Potential at point B in circuit A is |
(Y) .5A |

In the circuit shown below the reading of ammeter is the same when both switches open as both switches close.

The value of resistance R is

(a) 800Ω

(b) 900Ω

(c) 1200Ω

(d) 1000Ω

Solution

A 20µF capacitor which is initially uncharged is connected to a 6V battery through a resistor with resistance equal to 200Ω

Magnitude of final charge q

How long would it take for capacitor to be charged to (1/2)q

(a) 3.8×10

(b) 2.8×10

(c) 2.8×10

(d) 3.8×10

The time taken by the capacitor to be charged to 0.80q

Solution 24-26

In the figure given below the circuit contains four capacitors having same capacitance of 10µF and a battery providing a voltage of 90V

Match the columns given below

Column A |
Column B |

(P) When switch S_{2} is open and S_{1} is closed and then opened after C_{1} , C_{2} and C_{3} are fully charged. Electric potential difference across each capacitor is |
(W) 0 V |

(Q) Now after opening S_{1} if switch S_{2} is closed, the electric potential difference across each capacitor is |
(X) V_{1}=V_{3}=36V , V_{2}=V_{4}=18V |

(R) In another case if switch S_{1} is open and switch S_{2} is first closed then electric potential difference across each capacitor is |
(Y) V=30 V |

(S) Now if switch S_{1} is closed , the potential difference across each capacitor is |
(z) V_{1}=V_{3}=30V , V_{2}=V_{4}=15V |

Kirchhoff's junction rule is a reflection of

(a) conservation of current density vector.

(b) conservation of charge.

(c) the fact that the momentum with which a charged particle approaches a junction is unchanged (as a vector) as the charged particle leaves the junction.

(d) the fact that there is no accumulation of charges at a junction

Solution

- Introduction
- |
- ElectroMotive Force(emf)
- |
- Internal Resistance of Battery (or cell)
- |
- Electric Energy and Power
- |
- Kirchoff's Rules
- |
- The junction Rule (or point rule)
- |
- The Loop Rule (or Kirchoff's Voltage Law)
- |
- Grouping of the cell's
- |
- Meterbridge (slide wire bridge)
- |
- Potentiometer
- |
- Comparison of EMF's of two cells using potentiometer
- |
- Determination of internal resistance of the cell

Class 12 Maths Class 12 Physics

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