Internal resistance and potential divider

Multiple Choice

Name the material used for making potentiometer wire

• Copper

• Aluminium

• Brass

• Manganin

• silver

Multiple Choice

Why potentiometer is preferred to Voltmeter for measurement of emf?

• long wire is used

• null method

• no special advantage

• Alloys are used in potentiometer wire

Multiple Select

Essential condition for working of potentiometer circuit

• Positive terminal cells in the primary circuit and secondary circuit are connected to same point

• Emf of cell in the primary circuit has to be greater than that of a cell in the secondary circuit

• Connections must be neat and tight

• Current flowing through the wire must be constant

Multiple Choice

A battery has an e.m.f of 6.0 V. When it is connected to an external resistor, the potential different is 2.6 V and the current is 0.6 A. 
What is the value of the internal resistance?

• 3.4 Ω
• 4.3 Ω
• 4.4 Ω
• 5.7 Ω

Multiple Choice

What is the effect of internal resistance on the voltage across the terminals of a power supply as the supplied current increases?

• The voltage increases

• The voltage decreases

• The voltage remains constant

• The voltage fluctuates

Multiple Choice

What is the formula for the potential difference across a power source?

• V = E - Ir

• V = E + Ir

• V = E / Ir

• V = E * Ir

Multiple Choice

Each headlamp is rated as ‘12 V, 36 W’. Calculate the resistance of a headlamp.

• 0.5 Ω

• 4 Ω

• 3 Ω

• 1 Ω

Multiple Choice

A car battery has an e.m.f. of 12 V and an internal resistance of 0.04 Ω. The starter motor draws a current of 100 A. Calculate the terminal p.d. of the battery when the starter motor is in operation.

• 1.5 V

• 12 V

• 3.0 V

• 0.04 V

Multiple Choice

Charlie and Mira are working on a fun project. Can you help them figure out in which type of circuit they would most likely find an LDR?

• Temperature sensing circuit

• Light sensing circuit

• Pressure sensing circuit

• Humidity sensing circuit

Multiple Choice

During a science fair, Thomas and Evie were discussing electronic components. Can you help them figure out what LDR stands for?

• Light Dependent Resistor

• Low Density Resistor

• Light Density Resistor

• Low Dependent Resistor

Open Ended

Explain how a potentiometer can be used to compare potential differences between two resistors.

Multiple Choice

What is the relationship between the e.m.f.s of two cells when using a potentiometer?

• The e.m.f.s are equal

• The e.m.f.s are inversely proportional

• The ratio of e.m.f.s is equal to the ratio of lengths

• The e.m.f.s are unrelated