Science case /data -based (4 Marks)

Read the following and answer any three questions from (i) to (iv).
Andre Marie Ampere suggested that a magnet must exert an equal and opposite force on a current carrying conductor, which was experimentally found to be true. But we know that current is due to charges in motion. Thus, it is clear that a charge moving in a magnetic field experience a force, except when it is moving in a direction parallel to it. If the direction of motion is perpendicular to the direction of magnetic field, the magnitude of force experienced depends on the charge, velocity (v), strength of magnetic field (B), and sine of the angle between v and B. Direction of magnetic force is given by Fleming's left-hand rule.

1. If an electron is travelling horizontally towards east. A magnetic field in vertically downward direction exerts a force on the electron along which side?
    
2. If a charged particle is moving along a magnetic field line. The magnetic force on the particle will?
    
3. a) A magnetic field exerts no force on?
   b) what Andre Marie Ampere suggested?
    
4. What is fleming's left hand rule?

1. The figure shows a domestic electric circuit. Study this circuit carefully and list any three errors in the circuit and justify your answer.
2. Give one difference between the wires used in the element of an electric heater and in a fuse.
3. List two advantages of parallel connection over series connection.1 image attached.

The wire in Figure below is being moved downwards through the magnetic field so as to produce induced current.

What would be the effect of:

1. Moving the wire at a higher speed?
2. Moving the wire upwards rather than downwards?
3. Using a stronger magnet?
4. Holding the wire still in the magnetic field?
5. Moving the wire parallel to the magnetic field lines?

Read the following and answer any three questions from (i) to (iv).An insulated copper wire wound on a cylindrical cardboard tube such that its length is greater than its diameter is called a solenoid. When an electric current is passed through the solenoid, it produces a magnetic field around it. The magnetic field produced by a current-carrying solenoid is similar to the magnetic field produced by a bar magnet. The field tines inside the solenoid are in the form of parallel straight tines. The strong magnetic field produced inside a current-carrying solenoid can be used to magnetise a piece of magnetic material, like soft iron, when placed inside the solenoid. The strength of magnetic field produced by a current carrying solenoid is directly proportional to the number of turns and strength of current in the solenoid.

1. The strength of magnetic field inside a long current-carrying straight solenoid is called?
    
2. The north-south polarities of an electromagnet can be found easily by using which rule?
    
3. Define a solenoid?
    
4. A long solenoid carrying a current produces a magnetic field B along its axis. If the current is double and the number of turns per cm is halved, then new value of magnetic field will be?

You are given the following current- time graphs from two different sources:
Now, answer the following questions:

1. Name the type of current in two cases.
2. Identify any one source for each type of these currents.
3. What is the frequency of current in case (b) in India?

Use above graphs to write two differences between the current in two cases.

Read the following and answer any three questions from (i) to (iv).
An electric motor is a rotating device that converts electrical energy into mechanical energy. Electric motor is used as an important component in electric fans, refrigerators, mixers, washing machines, computers, MP3 players, etc.

An electric motor consists of a rectangular coil ABCD of insulated copper wire. The coil is placed between the two poles of a magnetic field such that the arm AB and CD are perpendicular to the direction of the magnetic field. The ends of the coil are connected to the two halves P and Q of a split ring. The inner sides of these halves are insulated and attached to an axle. The external conducting edges of P and Q touch two conducting stationary bushes X and Y, respectively, as shown in the figure. Commercial motors use an electromagnet in place of a permanent magnet, a large number of turns of conducting wire in the current carrying coil and a soft iron core on which the coil is wound.

1. State the use of split rings.
    
2. Which has no effect on the size of the turning effect on the coil of an electric motor?
    
3. a) When current is switched ON, an electric fan converts into?
   b) In an electric motor, device that makes contact with the rotating rings and through them to supply current to coil is called?
   OR
4. What is the uses of electric motor?

Electrical devices often have an ampere marking to indicate the strength of electric current
required for it to work.
10. Will there be any change in the ammeter reading if the length of the wire in the circuit is doubled?
Explain your answer.

Leena creates an electric circuit with three resistors R1, R2 and R3.

9. Which wire should be connected to the negative terminal of a socket?

Sonia creates four electromagnets by placing iron bars in four different solenoids.
She brings a bunch of steel pins near each electromagnet.

5. Which electromagnet will attract the maximum number of pins?
A. Electromagnet 1
B. Electromagnet 2
C. Electromagnet 3
D. Electromagnet 4
6. Which of these must Sonia keep the same for her activity?
Circle ‘Yes’ or ‘No’ for the correct response.

Should this be kept the same?	Yes or No
Thickness of the wires	Yes/No
Voltages of the batteries	Yes/No
Thickness of the iron bars	Yes/No

7. Label the north pole and south pole of the electromagnet in the diagram.

8. Which of these devices works due to the magnetic effect of electric current?
A. LED bulb
B. Electric bell
C. Electric heater
D. Mobile charger

Reema placed a magnetic needle in an electric circuit.
She noticed a delection of the needle when the circuit is turned ON.

3. Reema placed a second battery in the circuit and turned the circuit ON.
What change in the needle will she observe now?
A. The needle will keep spinning.
B. The delection of the needle will increase.
C. The delection of the needle will decrease.
D. There will be no change in the delection of the needle.
4. Reema reverses the direction of the battery in the circuit.
She turns the circuit ON.
Draw an arrow on the magnetic needle to show the correct delection.

2. Which of these statements is true for the lines of a magnetic ield?
Circle ‘Yes’ or ‘No’ for the correct response.

Is the statement true?	Yes or No
Lines of a magnetic ield can sometimes cross each other.	Yes/No
Lines of a magnetic ield emerge from the north pole and meet at the south pole.	Yes/No
Lines of a magnetic ield can sometimes change direction.	Yes/No

Which of these magnets has the strongest magnetic field?