Objective Type Questions
Q1: The strength of an electromagnet after the limit cannot be increased by increasing the current through the solenoid. What is the reason behind this phenomenon?
(a) Electrons start to corrode the solenoid.
(b) Voltage through the solenoid gradually starts to decrease.
(c) Resistance of the solenoid increases.
(d) Current flowing through the solenoid is saturated.
Q2: A proton enters a magnetic field at right angle to it, as shown below. The direction of force acting on the proton will be:
(a) To the right
(b) To the left
(c) Out of the page
(d) Into the page
Q3: The magnetic field strength of a solenoid can be increased by inserting:
(a) a wooden piece into it.
(b) an iron piece into it.
(c) a glass piece into it.
(d) paper roll into it.
Q4: Rashita and her friends were decorating the class bulletin board.
She accidently dropped the box of stainless steel pins by mistake. She tried to collect the pins using a magnet. She could not succeed. Why?
(a) They are not using the magnet in right direction
(b) Steel pins are very heavy and cannot be lifted magnet
(c) Steel pins are very long
(d) Steel is not magnetic in nature
Q5: Which of the following correctly describes the magnetic field near a long straight wire ?
(a) The field consists of straight lines perpendicular to the wire.
(b) The field consists of straight lines parallel to the wire.
(b) The field consists of radial lines originating from the wire.
(d) The field consists of concentric circles centred on the wire.
Q6: Which of the following combination is not correct?
(a) Electric Motor—Fleming's right hand rule
(b) Electric generator—Electromagnetic induction
(c) Earth wire—Green colour
(d) Compass Needle—Small Magnet
Q7: If the current is passing through a straight conductor. then, the magnetic field lines around it forms a particular shape. That shape is:
(a) Straight lines
(b) Concentric circles
(c) Concentric ellipse
(d) Concentric parabolas
Q8: A 3 pin mains plug is fitted to the cable for a 1 kW electric kettle to be used on a 250 V a.c. supply which of the following statements is not correct?
(a) The fuse should be filled in the live wire.
(b) A 13 A fuse is the most appropriate value to use.
(c) The neutral wire is coloured black.
(d) The green wire should be connected to the earth pin.
Q9: In the given electric circuit, the device X is:
(a) Ammeter
(b) Resistance
(c) Galvanometer
(d) Voltmeter
Q10: The strength of magnetic field inside a long current carrying straight solenoid is:
(a) more at the ends than at the centre.
(b) minimum in the middle.
(c) uniform at all points.
(d) found to increase from one end to the other.
Very Short Answer Type Questions
Q11: Why does a current-carrying conductor experience a force when it is placed in a magnetic field?
Q12: What is the shape of a current-carrying conductor whose magnetic field pattern resembles that of a bar magnet ?
Q13: How is the strength of the magnetic field at a point near a wire related to the strength of the electric current flowing in the wire ?
Q14: Define magnetism.
Q15: Define electromagnetic induction.
Q16: A stationary charge is placed in a magnetic field. Will it experience a force ? Give reason to justify your answer.
Q17: What happens to the magnetic field lines due to a current carrying conductor when the current is reversed ?
Q18: Name five main parts of a D.C. motor.
Q19: Where will be the value of magnetic field maximum due to current-carrying circular conductor?
Q20: State the conclusion that can be drawn from the observation that a current-carrying wire deflects a magnetic needle placed near it.
Long Answer Type Questions
Q21: (a) What is the function of an earth wire in electrical instruments? Why is it necessary to earth the metallic electric appliances?
(b) Explain what is short-circuiting and overloading in an electric supply.
(c) What is the usual capacity of the fuse wire in the line to feed:
(i) lights and fans?
(ii) appliances of 2 kW or more power?
Q22: (a) State Fleming’s left hand rule.
(b) Write the principle of working of an electric motor.
(c) Explain the function of the following parts of an electric motor.
(i) Armature (ii) Brushes (iii) Split ring
Q23: (a) Explain what is the difference between direct current and alternating current? Write one important advantage of using alternating current.
(b) An air conditioner of 2 kW is used in an electric circuit having a fuse of 10 A rating. If the potential difference of the supply is 220 V, will the fuse be able to withstand, when the air conditioner is switched on? Justify your answer.
Q24: (a) State the function of ‘a fuse’ in an electric circuit. How is it connected in the domestic circuit?
(b) An electric fuse of rating 3A is connected in a circuit in which an electric iron of power 1.5 kilo watt is connected which operates at 220 V. What would happen? Explain.
Q25: (a) Explain any three properties of magnetic field lines.
(b) Give two uses of magnetic compass.
Q26: Explain the meanings of the words “electromagnetic” and “induction” in the term electromagnetic induction. List three factors on which the value of induced current produced in a circuit depends. Name and state the rule used to determine the direction of induced current. State one practical application of this phenomenon in everyday life.
Q27: (a) An electric current is passed in a horizontal copper wire from east to west. Explain your observations when a compass needle is placed (i) below this wire, (ii) above the wire. Draw inference from your observations.
(b) List the factors on which the strength of the magnetic field due to a straight conductor carrying current depend. How should these be changed to decrease magnetic field at a point?
Q28: (a) Name two electrical appliances of daily use in which electric motor is used.
(b) Name and state the principle on which an electric motor works.
Q29: (a) What is an electromagnet? What does it consist of?
(b) Name one material in each case which is used to make a : (i) permanent magnet (ii) temporary magnet.
(c) Describe an activity to show how you can make an electromagnet in your school laboratory.
Q30: (a) A coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is:
(i) pushed into the coil with its north pole entering first?
(ii) withdrawn from inside the coil?
(iii) held stationary inside the coil?
(b) Name the above phenomenon and mention the name of the scientist who discovered it. State the law that relates the direction of current in the coil with the direction of motion of the magnet.
You can access the solutions to this worksheet here.
85 videos|437 docs|75 tests
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1. What are the magnetic effects of current? |
2. How can we demonstrate the magnetic field produced by a current-carrying conductor? |
3. What is the right-hand thumb rule in the context of magnetic effects of current? |
4. What is an electromagnet and how does it work? |
5. How does the strength of the magnetic field change with the amount of current? |
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