Required Practicals Flashcards
RP1
What piece of apparatus can be used to generate a wave in string?
Vibration generator driven by a signal generator
RP1
Why should the signal generator be left for 20 minutes before use?
To stabilise frequency
RP1
Safety measures for stationary wave on string
Stand could topple and injure, use counterweight
RP1
How can tension in a string be varied?
Change masses hanging from pulley
RP1
How can uncertainty be reduced to do with length of string?
Longer string, lower uncertainty
RP1
Equation for wave speed, mass per unit length and tension in string
C = √(T/m)
RP1
When plotting L against T, how can you work out wave speed?
2 times gradient
RP2
What safety precautions should be taken when operating a laser?
Never look directly at the bean
Ensure no reflective surfaces
Display a warning sign ⚠️
RP2
How should you measure the fringe spacing of an interference pattern?
Measure across 11 fringes for 10 fringe spacings
Reduced uncertainty
RP2
Equation for double slit:
Wavelength=?
Wavelength= (w×s)/D
RP2
How do you work out wavelength?
Plot w against D
Gradient × s is wavelength
RP2
Describe interference pattern if white light used instead of monochromatic
Central white fringe. Other fringes: spectra blue light closest to centre, red furthest from centre
RP3
What is g?
Gravitational field strength
g=9.81 on earth
RP3
What is free fall?
Only force acting on an object is gravity
RP3
What graph can be plotted to determine g?
2s/t against t
Gradient is g
RP3
How should you reduce air resistance?
Use a small ball bearing
RP5
State equation used to calculate resistivity of a wire
P=(RA)/L
RP5
What is the unit of resistivity?
Ohm meters
RP5
How does the resistance of a wire change when the length is decreased?
Length of wire decreases, resistance decreases
RP5
How does the resistance of a wire change when the cross sectional area is decreased?
Area decreases, resistance increases
RP5
Why should the power supply be switched off between readings?
Temperature of wire should remain constant so turning off will stop wire heating too much
RP5
How should resistivity be calculated using a graph?
Plot R against L
Gradient=R/L
Resistivity= gradient × A