4.3 Electrical Circuits Flashcards
What is Kirchhoff’s first law?
The sum of currents entering a junction (or node) in a circuit is equal to the sum of the currents leaving the junction
What is Kirchhoff’s second law?
In any closed loop, the sum of the emf is equal to the sum of the products of the current and resistance.
What is the potential divider equation?
Vout= Vin x R2/(R1+R2)
What are the variations on a potential divider circuit?
Variable resistor
Thermistor
LDR
What is a potential divider circuit?
It uses two resistors in series to split or divide the voltage of the supply in a chosen ratio so that a chosen voltage can be provided to another device or circuit.
What is terminal pd?
The potential difference recorded across the terminals of a cell.
What are lost volts?
The difference between the emf and the terminal pd when charge flows
what is internal resistance?
The resistance to electric current of the materials inside a source. When current flows, energy is transferred to these materials, resulting a drop in the terminal pd.
Equation for emf with r
e = I(R+r)
Define kilowatt hour
Energy transformed by a device working at 1kW for 1h
Explain why Resistivity rather than resistance of a material is given in tables of properties of materials.
p is independent of dimensions of the specimen of the material.
Why is it not advisable to maintain high currents for a long time?
Excessive heating of CELL/ energy wasted INTERNALLY
