Heating Effect of Electric Currents (DP IB Physics: SL)

A circuit contains five identical resistors and four identical voltmeters. The reading on voltmeter V₁ is 8.0 V and the reading on voltmeter V₂ is 1.0 V. What are the readings on V₃ and V₄?

A power cable X has resistance R and carries current I. A second cable Y has resistance 2R and carries current .

What is the ratio ?

Two resistors are connected to a cell.

Assuming both resistors are made from wires of the same length, which graph shows how the potential V varies along the line XY?

Kirchhoff’s laws are applied to the circuit shown.

What is the equation for the dotted loop?

In the circuit shown, the fixed resistor has a value of 3 Ω and the variable resistor varies between 0 Ω and 12 Ω.

The power supply has an emf of 15 V and negligible internal resistance.

What is the range of potential differences V which can be measured across the 3 Ω resistor?

Four resistors are connected to a battery of e.m.f. 6 V as shown.

If the battery has negligible internal resistance, what is the current in the battery?

Which of the following cannot be the units for resistivity?

Three resistors are connected to a cell of e.m.f. 10 V and negligible internal resistance as shown.

What is the power dissipated in one of the 2 Ω resistors and in the whole circuit?

Three identical lamps, W, X and Y are connected to a cell of negligible internal resistance as shown.

When the switch is closed, each lamp is lit. Which of the following correctly describes the brightness of lamps W, X and Y when the switch is opened?

A science student who lives in the UK, where the mains voltage is 240 V, buys a light bulb marked 60 W which she uses in her bedroom. The student takes the lightbulb with her on a trip to Canada where the mains voltage is 100 V and also uses it there.

Which line correctly identifies the approximate power dissipated in the bulb in the UK and Canada?

What is the current reading on the ideal ammeter shown?

What is the current reading on the ideal ammeter shown?

A student is investigating the properties of cells made using lemons. They find that their lemon cell has an emf of 1.0 V and internal resistance 5000 Ω. The student wonders what the least number of lemons they would need to light a bulb with a rating of 5.0 W and 8.0 V.

What is the best estimate of the least number of lemons?

The diagram shows a cubical wire framework made from rigid, uniform copper wire. The wires all have the same length.

Points A and H are connected to the terminals of a 6.0 V power supply. Side AB has a resistance of 2.0 Ω.

Which line correctly identifies the total resistance of the network, the potential at F and the current in BC?

	total resistance / Ω	current in side BC / A	potential at F / V
A.		3.6	6.0
B.		0.6	2.4
C.		1.2	3.6
D.		0.6	6.0

The circuit shown includes three identical cylindrical resistors, with dimensions such that the cross-sectional area is 5 mm², the length is 20 cm and the resistance is R Ω.

When the switch is closed, the total resistance of the circuit is 5 kΩ.

What is the resistivity of the material that the resistors are made from?

The readings on both ammeters are zero. What are the values of X and Y?

A strain gauge is a device which measure force. An applied tension on a thin wire of known resistance changes the length and cross-sectional area so that the value of the resistance is changed in a predictable way (assuming that volume remains constant).

When the length of the wire is increased by 5 % what will be the effect on the resistance?

Two rods have the same length, and the same resistance. One rod is made from copper and the other from aluminium.

Copper is three times as dense as aluminium but has half the value of resistivity.

A student wants to know the ratio of:

Which option is the correct answer?

The identical resistors marked (i), (ii), (iii) and (iv) are connected as shown. The battery which has negligible internal resistance supplies a total power of 20 W. 

What is the power dissipated in resistor (iv)?

A circuit contains five identical resistors and four identical voltmeters. The reading on voltmeter V₁ is 8.0 V and the reading on voltmeter V₂ is 1.0 V. What are the readings on V₃ and V₄?