Lakhmir Singh

An electric lamp of 100 Ω, a toaster of resistance 50 Ω, and a water filter of resistance 500 Ω are connected in parallel to a 220 V source. What is the resistance of an electric iron connected to the same source that takes as much current as all three appliances, and what is the current through it?

A circuit diagram may be used to demonstrate the electric lamp, toaster, and water filter linked in parallel to a 220 V source: The resistors' equivalent resistance may be computed as follows:...

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A man driving a car can read a distant road sign clearly but finds difficulty in reading the odometer on the dashboard of the car. Which of the following statement is correct about this man?
a) the near point of his eyes has receded away
b) the near point of his eyes has come closer to him
c) the far point of his eyes has receded away
d) the far point of his eyes has come closer to him

The correct answer is a) his eyes' near point has receded.

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A student sitting on the last bench in the class cannot read the writing on the blackboard clearly but he can read the book lying on his desk clearly. Which of the following statement is correct about the student?
a) the near point of his eyes has receded away
b) the near point of his eyes has come closer to him
c) the far point of his eyes has receded away
d) the far point of his eyes has come closer to him

The correct answer is d) his eyes' distant point has moved closer to him

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(a) What is buckminsterfullerene? How is it related to diamond and graphite? (b) Why is diamond used for making cutting tools but graphite is not? (c) Why is graphite used for making dry cell electrodes but diamond is not?

Solution: (a) Buckminsterfullerene is a carbon allotrope with 60 carbon atom clusters linked together to create spherical molecules. Nothing is left behind when it burns to generate carbon dioxide...

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Buckminsterfullerene is a spherical molecule in which 60 carbon atoms are arranged in interlocking hexagonal and pentagonal rings of carbon atoms. (a) How many hexagons of carbon atoms are present in one molecule of buckminsterfullerene? (b) How many pentagons of carbon atoms are present in one molecule of buckminsterfullerene?

Solution: (a) One buckminsterfullerene molecule contains 20 hexagonal carbon rings. (b) One buckminsterfullerene molecule contains 12 pentagonal carbon rings.

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a) State what would happen to the direction of rotation of a motor if:
i) the current were reversed
ii) the magnetic field were reversed
iii) both current and magnetic field were reversed simultaneously
b) In what ways can a motor be made more powerful?

Answer: a) i. As a result of reversing the current, the direction of rotation would be reversed. a) I If the current is reversed, the direction of rotation would be reversed. ii. It should be noted...

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a) A current-carrying conductor is placed perpendicularly in a magnetic field. Name the rule which can be used to find the direction of force acting on the conductor.
b) State two ways to increase the force on a current-carrying conductor in a magnetic field.

Answer: (a) The Fleming left-hand rule can be used to find the direction of force applied on a current-carrying conductor. (b) Increasing the current flow in a conductor in a magnetic field...

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Long Answer Type Questions: c) What is the shape of field lines inside a current-carrying solenoid? What does the pattern of filed lines inside a current-carrying solenoid indicate?
d) List three ways in which the magnetic field strength of a current-carrying solenoid can be increased?

Answer: c) When the magnetic field lines inside a current-carrying solenoid are parallel to one another and in straight lines, the magnetic field inside the solenoid is uniform. d) When employing a...

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Long Answer Type Questions: a) What is a solenoid? Draw a sketch to show the magnetic field pattern produced by a current-carrying solenoid.
b) Name the type of magnet with which the magnetic field pattern of a current-carrying solenoid resembles.

Answer: a) A solenoid is described as a lengthy coil of insulated copper wire that contains a large number of near turns and is used to operate a motor. b) It has been demonstrated that the magnetic...

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a) Draw a sketch to show the magnetic lines of force due to a current-carrying straight conductor.
b) Name and state the rule to determine the direction of magnetic field around a straight current-carrying conductor.

Answer: a) The diagram required: b) Maxwell's right hand rule is used to determine the magnetic field direction around a straight current-carrying wire. The thumb points in the direction of the...

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