Crucial definitions Flashcards
What is a scalar quantity
A quantity with size only.
- Temperature
- Mass
- Speed
What is a vector quantity
A quantity with size and direction
- Gravity
- Force
- Acceleration
What is DC current
Current that flows in one direction only
What is AC current
Current that changes direction 50 times per second
What does energy transferred =
Work done
What is an unbalanced force?
Unbalanced force = mass * acceleration
Changes speed and changes direction
What are he similarity’s of the electromagnetic spectrum?
- Travel at the same speed in a vacuum
- All transverse waves
- All electromagnetic waves
What are the differences of electromagnetic waves?
- All have different frequency
- All have different wavelength
Why would we use parallel circuits?
- Control each component separately
- If on component blows, the others still work
How do you know whether the ray light goes towards or away from the normal in refraction?
- Less to more dense material it bend towards the normal
- More to less dense material it bend away from the normal
What does an alternating magnetic field do?
- It produces a force
What its important to remember about ultrasound waves?
- Rely on reflections
- You always have to half the distance cause it goes to a point then come back
How to make ruler measurements more accurate?
-Make sure a ruler is at 90 degrees to avoid parallax.
What should you always try and do when explaining an equation?
-Always try to use an equation
Why does refractive index not have a unit?
-n=sin(i)/sin(r) tells me I am dividing two angles meaning the units cancel leaving NO units
Define an Unbalanced force
-The total force acting on an object after you have added them as vectors
What two things should you always talk about when talking about ionisation?
- Mass
- Charge
Define a half-life?
-Time taken for half of the radioactive nuclei to decay
What is precision?
- The scale (how precise)
What is the accuracy?
- Other variables which affect the experiment
What should you always talk about in a MOMENTUM question which asks ‘Explain why the cannon moves in the opposite direction.’
- Momentum = mass * velocity
- Momentum before firing is zero
- Momentum is conserved
- Firing canon must have an equal and opposite momentum to the cannonball
How does a loudspeaker produce a sound wave?
- Current in the coil is alternating current
- The coil has a changing magnetic field
- The magnetic field of the magnet and magnetic field of coil interact
- Producing a force on the coil
- Vibrate loudspeaker cone
What are two advantages of a circuit breaker?
- They can be reset unlike a fuse
- They cut off the circuit faster than a fuse
In a nuclear power station, what does the energy start as?
- Nuclear
