Electricity

• What is a series circuit?

  A circuit with only one path for current to flow
• What is a parallel circuit?

  A circuit with multiple paths for current to flow.
• Vs = V1 + V2…
• Is = I1 = I2…
• Rs = R1 + R2…
• Vp = V1 = V2…
• Ip = I1 + I2…
• 1/Rp = 1/R1 + 1/R2…
• What is current measured in?

  Amperes (A)
• What can measure the current?

  An ammeter placed in series to the circuit
• What is current? 


  The rate of flow of charge

  
• What is voltage (potential difference)?

  The transfer of one joule of energy per one coloumb

  
• What is potential difference measured in?

  Volts (V)
• How can you measure the voltage?

  A voltmeter in a parallel circuit to a component
• What is resistance? 


  The opposition of a current
• What is resistance measured in?

  Ohms (Ω)
• What is Ohm’s law?

  The potential difference across a fixed resistor at constant temperature is directly proportional to the current through it.

  
• How does the resistance effect the current?

  The greater the resistance of the band, the lower the share of current through the branch
• What is a direct current (d.c) supply?


  a flow of electric charge in only one direction
• What is an alternating current (a.c) supply? 


  a flow of electric charge that regularly reverses its direction
• What pattern does a d.c supply display on an oscilloscope?

  A straight line (if its not a varying d.c supply)

  
• What pattern does an a.c supply display on an oscilloscope?

  A varying line and will be in negative and positive

  
• What is power? 


  A measure of the energy transferred per unit of time

  
• What formula can you use to find the power when voltage and current are known?

  P=IV
• What formula can you use to find the power when resistance and current are known?

  P = I²R
• What formula can you use to find the power when voltage and resistance are known?

  P= V²/R
• What does a fuse do?

  It melts or ‘blows’ when a too high a current passes through it to protect other components
• What fuse should you use?

  One slightly higher than the current
• How can you work out what fuse to use?

  Use P=IV to work out the current then pick the right fuse (3A,13A)
• What is the UK’s declared potential difference?

  230V
• What is the UK’s frequency?

  50Hz
• What are features of parallel plates?

  • equal distance between the plates
  • the strength it the same throughout