Electricity as a phenomena
Explain the structure of atom
Atoms made up of neutrons, protons and electrons
What is current?
The rate of flow of electric charges in a circuit
What is voltage?
Electrical potential difference.
A small light bulb is connected to a 6 V battery and draws 2 A of current. What is the net resistance of the bulb?
3 Ohms
Explain what is happening to the ruler in this case:
After being rubbed, a plastic ruler attracts paper scraps.
Ruler carries electric charge. It exerts electric force on paper
What is the direction of current?
From positive to negative charge
What causes what: voltage causes current or current causes voltage?
Voltage causes current
A motor with an operating resistance of 32 Ohms is connected to a voltage source. The current in the circuit is 1.5 A. What is the voltage of the source?
48 Volts
What is the interaction between static electric charges
Electrostatics
What is the measurement of the elementary charge?
Coulombs
A restriction to current flow
The current passing through a resistor in a circuit is 0.01 A when the voltage across the same resistor is 5 V. What current passes through this resistor when the voltage across it is 7.5 V?
0.015 Amperes
What is induction?
The production of a charge in an uncharged body by bringing a charged object close to it.
What is the formula which connects current, charge and time?
I = Q/t
Show the formula for Ohm's law
I = V/R
If I=200 mA and V=125 V, what is the resistance (in \OmegaΩ) of the nichrome wire?
625 Ohms
A balloon has a negative charge when rubbed by woollen cloth.
During rubbing, what have been transferred between the woollen cloth and the balloon?
Electrons
How many electrons are in 1 C?
6*1018 electrins
What are the measurements for current, resistance and voltage?
Current is measured in Amperes
Resistance is measured in Ohms
Voltage is measured in Volts
It is known that the amount of current needed to flow through a human being in order to cause them to have ventricular fibrillation (heart attack) is about 100 mA.
What is the minimum voltage (in volts) that will cause a person who has a body resistance of 1723 Ohms to have ventricular fibrillation?
172.3 Volts