Section 16.2 Magnetic Effect Of Electric Current

Section 16.2 Magnetic effect of electric current • Current-carrying straight wire • Current-carrying circular coil • Current-carrying solenoid © Manhattan Press (H.K.) Ltd.

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16.2 Magnetic effect of electric current (SB p. 111)

Magnetic effect of electric current Magnetic field produced by • magnet • moving electric charges electric current magnetic effect of an electric current Go to © Manhattan Press (H.K.) Ltd.

Discussion 2

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16.2 Magnetic effect of electric current (SB p. 112)

Current-carrying straight wire Expt. 16B Magnetic effect of current A. Magnetic field due to current-carrying straight wire

straight vertical wire

low voltage d.c. power supply

plastic board

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16.2 Magnetic effect of electric current (SB p. 112)

Current-carrying straight wire Magnetic field — concentric circles with wire at centre

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16.2 Magnetic effect of electric current (SB p. 113)

Current-carrying straight wire

current o ut of the pla ne © Manhattan Press (H.K.) Ltd.

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16.2 Magnetic effect of electric current (SB p. 113)

Current-carrying straight wire

current into the plane © Manhattan Press (H.K.) Ltd.

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16.2 Magnetic effect of electric current (SB p. 113)

Right-hand grip rule for current-carrying straight wire field lines

magnetic field predicted by current

right-hand grip rule right hand

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16.2 Magnetic effect of electric current (SB p. 113)

Right-hand grip rule for current-carrying straight wire field lines

current

right hand

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16.2 Magnetic effect of electric current (SB p. 113)

Right-hand grip rule for current-carrying straight wire right hand

current

field lines

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16.2 Magnetic effect of electric current (SB p. 114)

Current-carrying circular coil Expt. 16B Magnetic effect of current B. Magnetic field due to current-carrying circular coil

d.c. power supply plastic board

circular coil © Manhattan Press (H.K.) Ltd.

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16.2 Magnetic effect of electric current (SB p. 114)

Current-carrying circular coil

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16.2 Magnetic effect of electric current (SB p. 115)

Right-hand grip rule for current-carrying circular coil Magnetic field points upwards

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Magnetic field points into paper

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16.2 Magnetic effect of electric current (SB p. 115)

Current-carrying solenoid Expt. 16B Magnetic effect of current C. Magnetic field due to current-carrying solenoid

solenoid

plastic board

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d.c. power supply

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16.2 Magnetic effect of electric current (SB p. 115)

Current-carrying solenoid uniform

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16.2 Magnetic effect of electric current (SB p. 116)

Right-hand grip rule for current-carrying solenoid

Thinking 4 © Manhattan Press (H.K.) Ltd.

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16.2 Magnetic effect of electric current (SB p. 117)

Example 1: The following figure shows a solenoid placed on a table. If two compasses are placed at X and Y on the table, draw the needles of the compasses when (a) switch K is open, and (b) switch K is closed. (The needles of the compasses point to the north.) (a)

(b)

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Solut ion

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To section 16.3

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16.2 Magnetic effect of electric current (SB p. 111)

Discussion 2:

1. With the help of a magnet, suggest a method to make an iron bar attract some paper clips. Ans Discuss with your classmates. (a) Touch the iron bar with the magnet, andwer then the iron bar can attract the paper clips. (b) Magnetize the iron bar by sliding the north pole of the magnet along the bar many times in the same direction. Then the iron bar can attract the paper clips. © Manhattan Press (H.K.) Ltd.

S

N

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16.2 Magnetic effect of electric current (SB p. 111)

Discussion 2: (Cont)

2. A compass is wound with several turns of a wire. The wire is connected to a dry cell to form a closed circuit. What happens to the needle of the compass? Discuss with your classmates. The needle is deflected.

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Ans wer

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16.2 Magnetic effect of electric current (SB p. 116)

Thinking 4

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The diagram shows two long and parallel current-carrying wires. Point Q is at equal distance from the two wires. Find the direction of the resulting magnetic fields at point P, Q and R. Ans magneticwer field

At Q, the by I1 is pointing out of the paper, but the magnetic field by I2 is pointing in of the paper. Therefore, there is no magnetic field at Q.

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