Electricity 3 Flashcards
(57 cards)
What is internal resistance?
Internal resistance is the resistance within a battery that causes energy loss due to electrons colliding with atoms, resulting in heat.
It is responsible for batteries warming up during use.
What causes internal resistance in batteries?
Internal resistance is caused by electrons colliding with atoms in the battery, leading to energy loss.
This energy loss manifests as heat.
What is electromotive force (e.m.f.)?
E.m.f. is the work done on each coulomb of charge, measured in volts, and is not a force.
It represents the energy supplied by the battery per unit charge.
What does the equation W = EQ represent?
W = EQ represents the work done (W) on a charge (Q) when subjected to an electromotive force (E).
W is measured in joules.
What is load resistance?
Load resistance (R) is the total resistance of all components in the external circuit, also referred to as external resistance.
It affects the current flowing in the circuit.
If there was no internal resistance, what would be the relationship between terminal p.d. and e.m.f.?
If there was no internal resistance, the terminal p.d. would be equal to the e.m.f.
In reality, internal resistance causes a voltage drop.
What is lost volts?
Lost volts is the energy wasted per coulomb overcoming the internal resistance of a battery.
It reduces the available voltage for the external circuit.
State the conservation of energy equation related to e.m.f. and internal resistance.
Energy per coulomb supplied by the source = Energy per coulomb used in load resistance + Energy per coulomb wasted in internal resistance.
What are the key equations related to e.m.f. and internal resistance?
The key equations are:
* E = V + V
* E = I(R + r)
* V = E - V
* V = I(r)
These equations can be rearranged based on given information.
How do you calculate the total e.m.f. of cells in series?
For cells in series, the total e.m.f. is calculated by adding the individual e.m.f.s of each cell.
Each charge gains e.m.f. from each cell it passes through.
What is the e.m.f. of identical cells in parallel?
For identical cells in parallel, the total e.m.f. remains the same as the e.m.f. of each individual cell.
The current splits equally between the cells.
What is the relationship between e.m.f., terminal p.d., and internal resistance?
The relationship can be described by the equation e = V + Ir, where e is e.m.f., V is terminal p.d., and r is internal resistance.
Fill in the blank: The energy wasted per coulomb overcoming the internal resistance is called the ______.
lost volts.
True or False: E.m.f. is a force.
False.
What is the gradient and intercept of the equation V = -rI + E?
The gradient is -r and the intercept is E.
This equation represents a straight line in a graph of voltage against current.
What should you do to find e.m.f. and internal resistance in a circuit experiment?
Measure the voltage across the load and current, record data, and plot results to analyze the relationship.
What is the potential difference across the load resistance?
The potential difference across the load resistance is the voltage drop when one coulomb of charge moves through the load.
What is the principle of conservation of charge in a circuit?
Charge doesn’t leak away; it is conserved. Whatever charge flows into a junction will flow out again.
According to Kirchhoff’s first law, what is the relationship between current entering and leaving a junction?
The total current entering a junction equals the total current leaving it.
What is the formula for charge flow at a junction if 6 coulombs of charge flow in and split in the ratio 1:2?
Q1 = 2C (I1 = 2A), Q2 = 4C (I2 = 4A)
What does Kirchhoff’s second law state?
The total e.m.f. around a series circuit equals the sum of the potential differences across each component.
Fill in the blank: In a closed loop, the quantities of energy must be equal if energy is _______.
conserved
What is the formula for the total resistance in a parallel circuit?
1/R_total = 1/R1 + 1/R2 + 1/R3
What is the current relationship in a parallel circuit?
Current is split at each junction: I = I1 + I2 + I3.
