Physics 4, 5, 6 Questions Flashcards
What does the live wire do?
It carries the high voltage
Which wire completes the circuit?
The neutral wire
What wire is a safety wire?
The earth wire
What does the earth wire stop from happening?
It stops appliances becoming live
With the polythene rod, where are electrons moved from and to?
Electrons move from the duster to the rod
With the Acetate rod, where are electrons moved from and to?
Electrons are moved from the rod to the duster.
What is Earthing?
When you prevent a dangerous spark from occurring by connecting a charged object to the ground using a conductor. No charge can build up by doing this.
How is paint sprayed to get an even coat when using an electrostatic paint sprayer?
- The spray gun is charged, which charges up the small drops of paint
- Each drop repels each other because they have the same charge
- The object is given the opposite charge, which attracts the paint drops
What frequency can humans hear up to?
20 000 Hz
What is ultrasound used for?
Breaking down accumulation in the body and for body scanning
Why is ultrasound better than X-Ray when looking at a foetus?
It is safer and doesn’t damage living cells. X-Rays are ionising radiation and can cause cancer if exposed to it at a high dose.
When a nucleus emits an alpha particle, what happens to the mass number and atomic number?
The mass number decreases by 4 and the atomic number decreases by 2.
When a nucleus emits a beta particle, what happens to the mass number and the atomic number?
The mass number doesn’t change (because it has lost a neutron but gained an electron) and the atomic number increases by 1 because it has one more proton.
What is half life?
The amount of time taken for half of the radioactive nuclei to decay.
What are the three medical uses of radiation?
- Radiotherapy (for treating cancer cells)
- Tracers in medicine
- Sterilisation of surgical instruments
How do smoke detectors work?
- A weak alpha source is put into the detector.
- The source causes ionisation of the air particles, which allows a current to flow
- When there is a fire, the smoke particles hit the alpha particles instead and reduces the current, making the alarm sound.