CHAPTER 12 MAGNETIC EFFECTS OF ELECTRIC CURRENT KSEEB SSLC CLASS 10 SCIENCE SOLUTIONS

CHAPTER 12 MAGNETIC EFFECTS OF ELECTRIC CURRENT KSEEB SSLC CLASS 10 SCIENCE SOLUTIONS English medium Karnataka state board,the Answers Are Prepared By Our Teachers Which Are Simple ,Pointwise,Easy To Read And Remember .

CHAPTER 12 MAGNETIC EFFECTS OF ELECTRIC CURRENT KSEEB SSLC CLASS 10 SCIENCE SOLUTIONS

Why does a compass needle get deflected when brought near a bar magnet?

– A compass needle is a small bar magnet itself.

– When brought near a bar magnet, the compass needle aligns with the magnetic field of the bar magnet.

– Like poles repel each other, causing the north pole of the compass needle to point towards the south pole of the bar magnet and vice versa.

– This deflection happens because magnetic fields interact, influencing the orientation of the compass needle.

– The end of the compass needle pointing north indicates the direction of the magnetic north pole due to this interaction.

Draw magnetic field lines around a bar magnet.

– Magnetic field lines emerge from the north pole and merge at the south pole.

– They form closed loops around the magnet.

– They are denser where the magnetic field is stronger.

– They do not intersect each other.

List the properties of magnetic field lines

– They emerge from the north pole and merge at the south pole of a magnet.

– They form closed loops.

– They are closer together where the magnetic field is stronger.

– They do not intersect each other.

. 3. Why don’t two magnetic field lines intersect each other?

– If they intersected, it would imply that a compass needle placed there would point in two different directions simultaneously, which is not possible.

– Each point in space should have a unique direction of the magnetic field, determined by the north-seeking pole of a compass needle.

– Hence, magnetic field lines do not cross to maintain the unique direction of the magnetic field at every point.

Consider a circular loop of wire lying in the plane of the table. Let the current pass through the loop clockwise. Apply the right-hand rule to find out the direction of the magnetic field inside and outside the loop.

– Current direction: Clockwise.

– Inside the loop: Using the right-hand rule, the magnetic field direction is into the plane of the table.

– Outside the loop: Using the right-hand rule, the magnetic field direction is out of the plane of the table.

The magnetic field in a given region is uniform. Draw a diagram to represent it..

Draw parallel straight lines indicating the magnetic field. Ensure they are evenly spaced and consistent in direction throughout the region

Choose the correct option. The magnetic field inside a long straight solenoid-carrying current

(a) is zero.

(b) decreases as we move towards its end.

(d) is the same at all points

ANSWER;-

– (d) is the same at all points.

Which of the following property of a proton can change while it moves freely in a magnetic field? (There may be more than one correct answer.)

(a) mass

(b) speed

(d) momentum

ANSWER;-

– (c) Velocity and (d) Momentum.

2.In Activity 12.7, how do we think the displacement of rod AB will be affected if (i) current in rod AB is increased;

(ii) a stronger horse-shoe magnet is used; and

(iii) length of the rod AB is increased?

– (i) Increasing current increases the force and displacement.

– (ii) A stronger magnet increases the force and displacement.

– (iii) Increasing rod length may increase displacement due to greater interaction with the magnetic field.

A positively-charged particle (alpha-particle) projected towards west is deflected towards north by a magnetic field. The direction of magnetic field is

(a) towards south

(b) towards east

(d) upward

ANSWER;-

– (b) Towards east.

Name two safety measures commonly used in electric circuits and appliances.

Safety measures commonly used in electric circuits and appliances:

– Earthing:Connecting metallic bodies of appliances to the earth via a green wire prevents electric shocks by providing a low-resistance path for current.

– Fuses: Fuses break the circuit in case of overcurrent, preventing damage to appliances and circuits due to short circuits or overloads.

. 2. An electric oven of 2 kW power rating is operated in a domestic electric circuit (220 V) that has a current rating of 5 A. What result do you expect? Explain

– Result: The oven consumes 2 kW of power, which at 220 V corresponds to a current of approximately 9.1 A (P = VI). This exceeds the circuit’s 5 A rating, potentially causing the fuse to blow or the circuit breaker to trip, preventing the oven from operating.

What precaution should be taken to avoid the overloading of domestic electric circuits?

– Balancing Loads: Distribute appliances across different circuits to ensure no single circuit exceeds its current rating.

– Avoiding daisy chaining: Plugging multiple appliances into a single socket through adapters or extensions can overload the circuit.

– Using circuit breakers: Ensuring circuits are equipped with circuit breakers to automatically disconnect power in case of overloads, preventing damage and hazards.

EXERCISES

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.

(d) The field consists of concentric circles centred on the wire.

– Answer: (d) The field consists of concentric circles centered on the wire.

– Explanation: The magnetic field around a long straight wire forms concentric circles when viewed from above the wire. This pattern is observed in Activity 12.1.

At the time of short circuit, the current in the circuit

(a) reduces substantially.

(b) does not change.

(d) vary continuously.

– Answer: (c) increases heavily.

– Explanation: A short circuit causes a sudden increase in current due to a direct connection between the live and neutral wires, bypassing the load. This is described in the section on domestic electric circuits.

State whether the following statements are true or false.

(a) The field at the centre of a long circular coil carrying current will be parallel straight lines.

(b) A wire with a green insulation is usually the live wire of an electric supply.

– (a) True

– Explanation: At the center of a long circular coil, the magnetic field lines are parallel straight lines, as discussed in the section about magnetic field due to a current in a circular loop.

– (b) False

– Explanation: A wire with green insulation is usually the earth wire (not live) in an electric supply setup, as mentioned in the domestic electric circuits section.

List two methods of producing magnetic fields.

– Methods:

Passing electric current through a straight conductor (Activity 12.1).
Creating a solenoid with multiple turns of wire (Section on magnetic field due to a current in a solenoid).

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

– Answer: When the direction of the current is perpendicular to the direction of the magnetic field. This maximizes the force, as explained using Fleming’s left-hand rule in Section 12.3.

Imagine that you are sitting in a chamber with your back to one wall. An electron beam, moving horizontally from back wall towards the front wall, is deflected by a strong magnetic field to your right side. What is the direction of magnetic field?

– Answer: The magnetic field direction is towards your right side.

– Explanation: According to the right-hand rule (applicable to electrons), if the electron beam moves horizontally and is deflected to the right by a magnetic field, the field direction is towards your right side.

State the rule to determine the direction of a

(i) magnetic field produced around a straight conductor-carrying current, (ii) force experienced by a current-carrying straight conductor placed in a magnetic field which is perpendicular to it, and

(iii) current induced in a coil due to its rotation in a magnetic field. 8. When does an electric short circuit occur?

ANSWER;-

– (i) Magnetic field around a straight conductor-carrying current: Use the right-hand thumb rule (Section 12.2.2).

– (ii) Force experienced by a current-carrying straight conductor in a magnetic field: Use Fleming’s left-hand rule (Section 12.3).

– (iii) Current induced in a coil due to its rotation in a magnetic field: Use Faraday’s law of electromagnetic induction (not explicitly mentioned, but inferred from the topic coverage).

When does an electric short circuit occur?

– Answer: A short circuit occurs when the live wire and the neutral wire come into direct contact, causing a sudden increase in current flow.

What is the function of an earth wire? Why is it necessary to earth metallic appliances?

– Answer: The earth wire is used for safety by providing a low-resistance path for leakage current to earth, preventing electric shocks especially in appliances with metallic bodies (Section on domestic electric circuits).

EXTRA POINTS;-

Effects of Electric Current:

– Heating effects: Electric current flowing through a conductor generates heat.

– Magnetic effects: Current-carrying wires act like magnets, deflecting compass needles.

– Electromagnetic induction: Moving magnets can induce electric currents.

– Electromagnetism link: Electric currents produce magnetic fields, showing the interrelation of electricity and magnetism.

Magnetic Field and Field Lines (12.1 – 12.2):

– Compass deflection: Compass needles align with magnetic fields, indicating magnetic poles (north and south).

– Magnetic field lines: Iron filings arrange in patterns around magnets, demonstrating magnetic fields.

– Field line characteristics: Magnetic field lines emerge from north and merge at south poles, never intersecting.

– Strength indication: Closeness of field lines indicates magnetic field strength.

– Field around current-carrying conductor: Electric currents through conductors produce concentric magnetic field lines.

– Right-Hand Thumb Rule: Determines the direction of magnetic field around a current-carrying wire.

– Field around a solenoid: Multiple turns of wire in a coil create a uniform magnetic field similar to a bar magnet.

Force on a Current-Carrying Conductor (12.3):

– Ampere’s discovery: Currents produce magnetic fields that exert forces on nearby magnets.

– Force direction: Depends on current and magnetic field orientation, demonstrated by Ampere’s experiments.

– Fleming’s Left-Hand Rule: Defines the direction of force on a current-carrying conductor in a magnetic field.

– Applications: Forces on conductors in fields are fundamental to devices like motors, generators, and speakers.