Physics 2 Flashcards
(33 cards)
Explain the electrostatic phenomena in terms of the movement of electrons.
In electrostatic phenomena, objects become charged through electron transfer (friction, contact induction). Electrons move from one object to another creating an electric field between the objects resulting in attractive or repulsive forces between charged objects. This results in observable effects on our environment.
Explain the potential dangers of electrostatic charge.
If the charge is large, a spark to the earth may happen unexpectedly, which can be dangerous. A build-up of static charge is a potential danger when refuelling aircraft or vehicles.
What is electric current in a solid metal conductor?
A flow of negatively charged electrons.
How can insulators be charged by friction?
When you rub two insulators together, you are rubbing electrons from one to another.
e.g. the negative cloth transfers electrons to the positive rod.
What are the forces of attraction between like and unlike charges?
Unlike charges attract; like charges repel.
How does a photocopier work?
- Inside a light-sensitive plate is given a negative charge. 2. An image of the original document is projected onto the plate. 3. The bright areas lose their charge. 4. While the dark areas keep it. 5. Powered ink (toner) is attracted to the charged areas (dark areas). 6. A blank sheet of paper is pressed against the plate and picks up the powered ink. 7. The paper is heated so the ink sticks to it. 8. The result is a copy of the original document.
How does an inkjet printer work?
An inkjet printer works by squirting lots of tiny charged ink droplets at the paper. To move the droplets up or down, a microchip varies the charge between two metal plates.
Explain how positive and negative electrostatic charges are produced on materials by the loss or gain of electrons.
The material that gains electrons becomes negatively charged. The material that loses electrons is left with a positive charge.
What is a circuit breaker?
Circuit breakers act as resettable fuses. They are automatically operated electrical switches that protect against electrical faults and stop the flow of electricity.
What is current?
Current is the rate of flow of charge (how fast the electrons flow through the wire).
What is Voltage?
Voltage is the energy amount per coulomb of charge.
How do you choose a fuse?
To choose a fuse of the right maximum current, select a fuse closest but above the normal operating current. Options are: 1A, 3A, 5A, 10A, 13A.
What is double insulation?
An extra layer of insulation used to hold multiple wires together, provide extra protection against damage, and provide extra insulation against shock.
What is insulation?
Insulation means putting a material that does not conduct electricity around a live conductor. It helps protect the wires from the environment and the environment from the wires.
What is Earthing?
Earthing is the process of connecting an object to the earth by a conductor so its excess charge is removed. It is used to protect you from electric shock.
How does current in a resistor result in the electrical transfer of energy and increase in temperature?
If a current flows through a resistor, the resistor will heat up. Electrons collide with ions to vibrate and heat up.
Different ways in which electrical heating is used in a variety of domestic contexts.
- Electrical storage heaters store heat overnight when electricity is cheaper and release it during the day. - Electrical boiler. - Direct electrical heaters. - Electrical underfloor heating.
Parts of a plug.
Earth wire connects the appliance to ground, allowing current to flow down to earth. Neutral wire completes the circuit by connecting back to the mains. Live wire current flows from mains to device. Outer insulation holds together and insulates the 3 wires. Fuse is a thin wire and a tube which melts when the current gets too high. Cable grip holds outer cable in place.
How can lamps and LEDs be used to indicate the presence of current in a circuit?
LEDs and lamps illuminate when current flows through them.
What is direct current?
Current flows only one way (electrons only want to go one way).
What is alternating current?
Current and voltage change direction on/off at a certain frequency. AC is used for mains electricity and power plant generators among other things.
Examples of electrical insulators.
- Plastic - Rubber - Wood - Glass
Examples of electrical conductors.
Metals such as - Copper - Gold - Silver - Iron
Why do insulators not conduct electricity?
The electrons are not free to move as they are bound in the atom and cannot carry charge.
