Subject

Physics

Class

CBSE Class 12

Pre Boards

Practice to excel and get familiar with the paper pattern and the type of questions. Check you answers with answer keys provided.

Sample Papers

Download the PDF Sample Papers Free for off line practice and view the Solutions online.

 Multiple Choice QuestionsShort Answer Type

1.

A resistance R is connected across a cell of emf element of and internal resistance r. A potentiometer now measures the potential difference between the terminals of the cell as V. Write the expression for 'r' in terms of straight epsilon , V and R. 


A resistance R is connected across a cell of emf element of and internal resistance r. A potentiometer now measures the potential difference between the terminals of the cell as V. Write the expression for 'r' in terms of straight epsilon , V and R. 

973 Views

2.

Figure shows two identical capacitors, C1 and C2, each of 1 μF capacitance connected to a battery of 6 V. Initially switch 'S' is closed. After sometime 'S' is left open and dielectric slabs of dielectric constant K = 3 are inserted to fill completely the space between the plates of the two capacitors. How will the (i) charge and (ii) potential difference between the plates of the capacitors be affected after the slabs are inserted? 
                          


Figure shows two identical capacitors, C1 and C2, each of 1 μF capacitance connected to a battery of 6 V. Initially switch 'S' is closed. After sometime 'S' is left open and dielectric slabs of dielectric constant K = 3 are inserted to fill completely the space between the plates of the two capacitors. How will the (i) charge and (ii) potential difference between the plates of the capacitors be affected after the slabs are inserted? 
                          

2936 Views

3.

The permeability of a magnetic material is 0.9983. Name the type of magnetic materials it represents.          


The permeability of a magnetic material is 0.9983. Name the type of magnetic materials it represents.          

1947 Views

4.

Two uniformly large parallel thin plates having charge densities +straight sigma and –sigmaare kept in the X-Z plane at a distance 'd' apart. Sketch an equipotential surface due to electric field between the plates. If a particle of mass m and charge '-q' remains stationary between the plates, what is the magnitude and direction of this field? 


Two uniformly large parallel thin plates having charge densities +straight sigma and –sigmaare kept in the X-Z plane at a distance 'd' apart. Sketch an equipotential surface due to electric field between the plates. If a particle of mass m and charge '-q' remains stationary between the plates, what is the magnitude and direction of this field? 

2622 Views

5.

Define the term 'wattless current'. 


Define the term 'wattless current'. 

1440 Views

6.

How are infrared waves produced? Why are these referred to as 'heat waves’? Write their one important use. 


How are infrared waves produced? Why are these referred to as 'heat waves’? Write their one important use. 

2064 Views

7.

A point charge Q is placed at point O as shown in the figure. Is the potential difference VA VB positive, negative, or zero, if Q is (i) positive (ii) negative? 


A point charge Q is placed at point O as shown in the figure. Is the potential difference VA VB positive, negative, or zero, if Q is (i) positive (ii) negative? 

6226 Views

8.

Two small identical electrical dipoles AB and CD, each of dipole moment 'p' are kept at an angle of 120o as shown in the figure. What is the resultant dipole moment of this combination? If this system is subjected to electric field (straight E with rightwards harpoon with barb upwards on top) directed along + X direction, what will be the magnitude and direction of the torque acting on this? 

        


Two small identical electrical dipoles AB and CD, each of dipole moment 'p' are kept at an angle of 120o as shown in the figure. What is the resultant dipole moment of this combination? If this system is subjected to electric field (straight E with rightwards harpoon with barb upwards on top) directed along + X direction, what will be the magnitude and direction of the torque acting on this? 

        

4090 Views

9.

A plane electromagnetic wave travels in vacuum along z-direction. What can you say about the direction of electric and magnetic field vectors?


A plane electromagnetic wave travels in vacuum along z-direction. What can you say about the direction of electric and magnetic field vectors?

1196 Views

10.

A magnetic needle free to rotate in a vertical plane parallel to the magnetic meridian has its north tip down at 60° with the horizontal. The horizontal component of the earth's magnetic field at the place is known to be 0.4 G. Determine the magnitude of the earth's magnetic field at the place.          


A magnetic needle free to rotate in a vertical plane parallel to the magnetic meridian has its north tip down at 60° with the horizontal. The horizontal component of the earth's magnetic field at the place is known to be 0.4 G. Determine the magnitude of the earth's magnetic field at the place.          

1779 Views