P4 - Radiation For Life Flashcards
P4 - Radiation For Life
Which direction do electrons move when a polythene rod is rubbed with a duster?
From duster to rod
P4 - Radiation For Life
Which direction do electrons move when an acetate rod is rubbed with a duster?
From rod to duster
P4 - Radiation For Life
What is a static charge caused by?
Electrons moving
P4 - Radiation For Life
What happens if enough static charge builds up?
It can suddenly move which can cause sparks or shocks that may be dangerous.
P4 - Radiation For Life
How can a charged conductor be discharged safely?
By connecting it to earth with a metal strap (earthing).
P4 - Radiation For Life
How does earthing work?
Electrons flow down strap to ground if charge is negative and flow up strap from ground if positive.
P4 - Radiation For Life
What are ions?
Atoms or molecules with a charge
P4 - Radiation For Life
How does static attract dust?
Dust particles are charged and attract opposite charge. Objects in home are insulators (get easily charged) and attract dust.
P4 - Radiation For Life
How does static affect clothing?
When synthetic clothes dragged (head or other clothes) electrons scrape off, leaving static charge - two attract. Little sparks/shocks as charges rearrange themselves.
P4 - Radiation For Life
What causes shocks from door handles?
Walking on nylon carpet with insulating soles builds up charge. Touching metal door handle/water pipe allows charge to flow via conductor - little shock.
P4 - Radiation For Life
How can static on clothing become dangerous?
Charge may become large enough to make a spark - dangerous near inflammable gases or fuel fumes.
P4 - Radiation For Life
When can static become dangerous (other than on clothes)?
Fuel flowing out of pipe, paper drags on rollers or grain shoots out of pipe, static builds up. If too big, might spark - explosion in dusty/fumey places (petrol station).
P4 - Radiation For Life
What kind of places is static dangerous in?
Areas with inflammable liquids or a high concentration of oxygen (hospital operating theatre)
P4 - Radiation For Life
How do anti-static sprays work?
Make surface of a charged object conductive - provides an easy path for charges to move away.
P4 - Radiation For Life
How do insulating mats and shoes work?
Prevent static electricity moving through them - stops human getting shocked.
P4 - Radiation For Life
How do paint sprayers work?
Spray gun charged and object given opposite to attract. Paint drops repel each other (fine spray).
P4 - Radiation For Life
What is the good thing about electrostatic paint sprayers?
Method gives even coat and hardly any paint wasted. No shadows - everywhere covered.
P4 - Radiation For Life
How do dust precipitators work?
Smoke particles reach chimney bottom, meet wire grid/rods with high voltage and (-) charge. Dust particles gain electrons (become (-)) Dust particles induce charge on earthed metal plates Dust attracted to metal plates - stick forming larger particles When heavy enough, particles fall off/knocked off with hammer Falls and is removed
P4 - Radiation For Life
How does a defibrillator work?
2 paddles to power supply: Paddles firmly on chest (good electrical contact) and charged up Everyone moves away - operator holds insulated handles Charge passes through paddles to patient - heart contracts.
P4 - Radiation For Life
If you increase the voltage….
more current will flow
P4 - Radiation For Life
If you increase the resistance…
less current will flow (or more voltage is needed to keep same current flowing)
P4 - Radiation For Life
Current only flows when?
As long as there is a complete loop - broke circuit means no current.
P4 - Radiation For Life
What does the live wire do?
Carries voltage. Alternates between a high + and - voltage of about 230V
P4 - Radiation For Life
What colour is the live wire?
Brown