Electric circuits

• How does a material become charged?

  Becomes negatively charged by gaining electrons

  Becomes positively charged by losing electrons
• What will two objects carrying the same type of charge do if they are brought close to each other?

  Repel each other
• What is an electric field?

  Region of space around a charged object in which another charged object will experience electrostatic force
• What happens to the strength of an electric field as you get further from the charged object?

  It decreases
• What is electric current?

  Rate of flow of charge
• What units are charge, current and time measured in?

  Coulombs (C) Amperes (A) Seconds (S)
• What is the same at all points when charge flows in a closed loop?

  current
• What must there be in a closed circuit so that electrical charge can flow

  Source of potential difference
• What happens to the current if the resistance is increased but the voltage stays the same?

  Current decreases
• What is an ohmic conductor?

  Conductor where current is directly proportional to the voltage so resistance is constant
• What happens to the resistance of a filament lamp as its temperature increases?

  Resistance increases
• What happens to the resistance of a thermistor as its temperature increases?

  Resistance decreases
• What happens to the resistance of a light-dependent resistor when light intensity increases

  Resistance decreases
• What are the main features of a series circuit?

  Single path for current flow
• What are the main features of a parallel circuit?

  Multiple paths for current flow
• Which two factors does the current depend on and what are their units?

  Resistance in ohms (Ω) Potential difference in volts (V)