Question

A simple circuit consists of a resistor connected to a battery. For each circuit, The battery has emf , internal resistance, and terminal voltage V, and the resistorhas resistance as shown below..

Rank the following circuits in order of current, from highest to lowest values.

Circuit 1)
EMF = 1.4 V
Internal Resistance = .2 ohms
Terminal Voltage = UNKNOWN
Resistor Resistance = 1.9 ohms

Circuit 2)
EMF = 1.4 V
Internal Resistance = .1 ohms
Terminal Voltage = 1.2 V
Resistor Resistance = UNKNOWN

Circuit 3)
EMF = 1.4 V
Internal Resistance = .1 ohms
Terminal Voltage = UNKNOWN
Resistor Resistance = 2 ohms

Circuit 4)
EMF = 1.4 V
Internal Resistance = UNKNOWN
Terminal Voltage = 1.2 V
Resistor Resistance = 2 ohms

Circuit 5)
EMF = Unknown
Internal Resistance = .1 ohms
Terminal Voltage = 1.4 V
Resistor Resistance = 2 ohms

Answer 1

The relation between emf and current isI = ε / R + r .........( 1)The relation between current and terminal voltage isV = ε - I r .......... (2)Here I = currentV is terminal voltageε is emfR is resistancer is internal resitanceFor circuit 1From equation (1)current passing through the circuit isI = emf / R + r= 1.4 V / 1.9Ω +0.2 Ω= 0.667 Afor circuit 2 isFrom equation (2)current passing through the circuit isI = ε - V / r= 1.4 - 1.2 / 0.1= 2 Afor circuit 3current passing through the circuit isI = 1.4 / 2+0.1= 0.667 Afor circuit 4I = ε / R= 1.4 / 2= 0.7 Afor circuit 5I = 1.4 V / 2= 0.7 Arancking in the order of current in the following circuits is2> 4 = 5 >1= 3