# A level Current Electricity Quiz 1

#### Quiz Description

In this quiz, we will be focussing on current electricity which we use daily for charging up electrical devices and use in circuits for light. It is used for such simple purposes because it is easy to connect and disconnect energy-using devices, this is because it is easy to convert mechanical and solar energy into electrical energy. Physics quizzes like this one often have technical problems and taking this quiz will help you understand more about current electricity.

Consider a current carrying wire current I in the shape of a circle. Note that as the current progresses along the wire, the direction of j (current density) changes in an exact manner, while die current/remain unaffected. The agent that is essentially responsible for is

Correct
• source of emf.
• electric field produced by charges accumulated on the surface of wire.
• the charges just behind a given segment of wire which push them just the right way by repulsion.

A resistance R is to be measured using a meter bridge. Student chooses the standard resistance S to be 100 Ω He finds the null point at l1 = 2.9cm. He is told to attempt to improve the accuracy. Which of the following is a useful way?

Correct
• He should measure l1 more accurately.
• He should change Sto 1000 Ω and repeat the experiment.
• He should change S to 3 Ω and repeat the experiment.
• He should give up hope of a more accurate measurement with a meter bridge.

Two cells of emf’s approximately 5 V and 10 V are to be accurately compared using a potentiometer of length 400 cm.

Correct
• The battery that runs the potentiometer should have voltage of 8 V.
• The battery of potentiometer can have a voltage of 15 V and R adjusted so that the potential drop across the wire slightly exceeds 10 V.
• The first portion of 50 cm of wire itself should have a potential drop of 10 V.
• Potentiometer is usually used for comparing resistances and not voltages.

Which of the following is wrong? Resistivity of a conductor is

Correct
• independent of temperature.
• inversely proportional to temperature.
• independent of dimensions of conductor.
• less than resistivity of a semiconductor.

For measurement of potential difference, a potentiometer is preferred over voltmeter because

Correct
• potentiometer is more sensitive than voltmeter.
• the resistance of potentiometer is less than voltmeter.
• potentiometer is cheaper than voltmeter.
• potentiometer does not take current from the circuit.

A Daniel cell is balanced on 125 cm length of a potentiometer wire. Now the cell is short-circuited by a resistance 2 ohm and the balance is obtained at 100 cm. The internal resistance of the Daniel cell is

Correct
• 0.5 ohm
• 1.5 ohm
• 1.25 ohm
• 4/5 ohm

When there is an electric current through a conducting wire along its length, then an electric field must exist

Correct
• outside the wire but normal to it.
• outside the wire but parallel to it.
• inside the wire but parallel to it.
• inside the wire but normal to it.

A charge is moving across a junction, then

Correct
• momentum will be conserved.
• momentum will not be conserved.
• at some places momenturii will be conserved and at some other places momentum will not be conserved.
• none of these.

An electric heater is connected to the voltage supply. After few seconds, current gets its steady value then its initial current will be

Correct
• equal to its steady current
• slightly higher than its steady current
• slightly less than its steady current
• zero

In the series combination of two or more than two resistances

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• the current through each resistance is same.
• the voltage through each resistance is same.
• neither current nor voltage through each resistance is same.
• both current and voltage through each resis¬tance are same.

Combine three resistors 5 Q, 4.5 Q and 3 Q in such a way that the total resistance of this combination is maximum

Correct
• 12.5 Q
• 13.5 Q
• 14.5 Q
• 16.5 Q

In parallel combination of n cells, we obtain

Correct
• more voltage
• more current
• less voltage
• less current

In a Wheatstone bridge if the battery and galvanometer are interchanged then the deflection in galvanometer will

Correct
• change in previous direction
• not change
• change in opposite direction
• none of these.

When a metal conductor connected to left gap of a meter bridge is heated, the balancing point

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• shifts towards right
• shifts towards left
• remains unchanged
• remains at zero

In a potentiometer of 10 wires, the balance point is obtained on the 7th wire. To shift the balance point to 9th wire, we should

Correct
• decrease resistance in the main circuit.
• increase resistance in the main circuit.
• decrease resistance in series with the cell whose emf is to be measured.
• increase resistance in series with the cell whose emf is to be determined.

The unit of emf is ___________.

Correct
• volt
• Joule
• Ampere
• Watt