English Medium कक्षा १० - CBSE Important Questions

State the law that explains the heating effect of current with respect to the measurable properties in an electrical circuit.

Anannya responded to the question: Why do electrical appliances with metallic bodies are connected to the mains through a three-pin plug, whereas an electric bulb can be connected with a two-pin plug?

She wrote: Three-pin connections reduce heating of connecting wires.

1. Is her answer correct or incorrect? Justify.
2. What is the function of a fuse in a domestic circuit?

Vinita and Ahmed demonstrated a circuit that operates the two headlights and the two sidelights of a car, in their school exhibition. Based on their demonstrated circuit, answer the following questions.

1. State what happens when switch A is connected to:
   a) Position 2
   b) Position 3
2. Find the potential difference across each lamp when lit.
3. Calculate the current.
   a) in each 12 Ω lamp when lit.
   b) In each 4 Ω lamp when lit.
   OR
4. Show, with calculations, which type of lamp, 4.0 Ω or 12 Ω, has the higher power.

Consider the following combinations of resistors:

1. 
   
2. 
   
3. 
   
4. 
   
   The combinations having equivalent resistance 1 Q is/are ______.

An electric iron of resistance 20 Ω draws a current of 5 A. The heat developed in the iron in 30 seconds is ______.

Study the following circuit:

On the basis of this circuit, answer the following questions:

i. Find the value of total resistance between the points A and B.

ii. Find the resistance between the points B and C.

iii. Calculate the current drawn from the battery, when the key is closed

OR

iii. In the above circuit, the 16Ω resistor or the parallel combination of two resistors of 8 Ω, which one of the two will have more potential difference across its two ends? Justify your answer.

Which of the following correctly describes the magnetic field near a long straight wire?

Name the rule for finding the direction of magnetic field produced by a straight current-carrying conductor.

When is the force experienced by a current-carrying conductor placed in a magnetic field largest?

Two coils A and B of insulated wire are kept close to each other. Coil A is connected to a galvanometer while coil B is connected to a battery through a key. What would happen if: 

a current is passed through coil B by plugging the key?  

Explain your answer mentioning the name of the phenomenon involved.

Two coils A and B of insulated wire are kept close to each other. Coil A is connected to a galvanometer while coil B is connected to a battery through a key. What would happen if: 

the current is stopped by removing the plug from the key? 

Explain your answer mentioning the name of the phenomenon involved. 

Derive the expression for the heat produced due to a current ‘I’ flowing for a time interval ‘t’ through a resistor ‘R’ having a potential difference ‘V’ across its ends. With which name is the relation known? How much heat will an instrument of 12W produce in one minute if it is connected to a battery of 12V?

Explain with the help of the pattern of magnetic field lines the distribution of the magnetic field due to a current-carrying a circular loop.

Why is it that the magnetic field of a current-carrying coil having n turns, is ‘n’ times as large as that produced by a single turn (loop)?

Draw magnetic field lines in and around a current-carrying straight solenoid.

The following diagram shows two parallel straight conductors carrying the same current. Copy the diagram and draw the pattern of the magnetic field lines around them showing their directions. What is the magnitude of the magnetic field at a point 'X' which is equidistant from the conductors? Give justification for your answer.

A simple motor is made in a school laboratory. A coil of wire is mounted on an axle between the poles of a horseshoe magnet, as illustrated.

In the example above, coil ABCD is horizontal and the battery is connected as shown.

1. For this position, state the direction of the force on the arm AB.
2. Why does the current in the arm BC not contribute to the turning force on the coil?

A circuit contains a battery, a variable resistor and a solenoid. The figure below shows the magnetic field pattern produced by the current in the solenoid.

1. State how the magnetic field pattern indicates regions where the magnetic field is stronger.
2. What happens to the magnetic field when the current in the circuit is reversed?

Ansari Sir was demonstrating an experiment in his class with the setup as shown in the figure below.

A magnet is attached to a spring. The magnet can go in and out of the stationary coil. He lifted the Magnet and released it to make it oscillate through the coil.
Based on your understanding of the phenomenon, answer the following question.

Is there any difference in the observations in the galvanometer when the Magnet swings in and then out of the stationary coil? Justify your answer.

A copper wire is held between the poles of a magnet

The current in the wire can be reversed. The pole of the magnet can also be changed over. In how many of the four directions shown can the force act on the wire?