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level: Electromotive force and internal resistance

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level questions: Electromotive force and internal resistance

QuestionAnswer
Internal resistance is caused by electrons colliding with atoms inside the battery, resulting in energy loss before the electrons leave the battery. It is represented as a small resistor inside the battery.Internal Resistance (r)
What causes internal resistance in a battery?Internal resistance is caused by electrons colliding with atoms inside the battery, leading to energy loss.
Electromotive force (emf) is the energy transferred by a cell per coulomb of charge that passes through it, represented as: ε = E/QElectromotive Force (emf)
How is emf defined?Electromotive force (emf) is the energy transferred by a cell per coulomb of charge, expressed as: ε = E/Q
The total resistance (R_T) in the circuit is the sum of the load resistance (R) and internal resistance (r) of the battery: R_t = R + rTotal Resistance (R_T)
How is total resistance (R_T) in a circuit calculated?The total resistance (R_T) is calculated as: R_t = R + r
The relationship between emf (ε), current (I), and total resistance is given by: ε = I(R + r)Relationship Between emf, Current, and Resistance
How is emf expressed in relation to current and resistance?Electromotive force (emf) can be expressed as: ε = I(R + r)
The potential difference (p.d) across the load resistor R is known as the terminal p.d (V).Terminal p.d (V)
What is the terminal p.d?The terminal p.d is the potential difference across the load resistor R.
The potential difference across the internal resistance r is known as lost volts (v), which represents the energy wasted by the cell per coulomb of charge.Lost Volts (v)
What are lost volts?Lost volts (v) is the potential difference across the internal resistance r, indicating the energy wasted by the cell per coulomb of charge.
The relationship between emf (ε), terminal p.d (V), and lost volts (v) is expressed as: ε = V + vRelationship of emf to Terminal p.d and Lost Volts
How can emf be expressed in terms of terminal p.d and lost volts?Electromotive force (emf) can be expressed as: ε = V + v
The emf of a battery can be measured by measuring the voltage across a cell using a voltmeter when there is no current running through the cell, indicating it is in an open circuit.Electromotive Force (emf)
How can the emf of a battery be measured?By measuring the voltage across a cell using a voltmeter when there is no current running through the cell.
The lost volts are the potential difference lost due to internal resistance in the battery, represented as Ir.Lost Volts
If a cell has an emf of 5 V and the value of lost volts is 2 V, what is the current of the resistor?First, write down what you know. Lost volts = Ir = 2V, Emf = 5V. Next, find the p.d across R using ε = IR + Ir. 5 = IR + 2, IR = 3V. Using V = IR, find the current. 3 = I x 10, I = 0.3. Therefore, I is 0.3 A.
The sum of the potential differences across the resistances in a circuit.Terminal Potential Difference (p.d)
For a cell with an emf of 10 V, a current of 2 A, R1 = 3 Ω, and R2 = 0.5 Ω, how do you find the terminal p.d?Calculate V1 = I × R1 = 2 × 3 = 6 V and V2 = I × R2 = 2 × 0.5 = 1 V. Thus, the total terminal p.d is 7 V.
The lost volts can be found using the formula ε = V + v.Lost Volts Calculation Definition
If the emf is 10 V and the terminal p.d is 7 V, what is the value of lost volts (v)?From the equation 10 = 7 + v, we find v = 3 V.
The internal resistance (r) of the cell can be calculated using the formula v = Ir.Internal Resistance
Given a current of 2 A and lost volts of 3 V, what is the internal resistance of the cell?Rearranging the formula gives r = v/I = 3/2 = 1.5 Ω.