light dependant resistors

• What is the symbol for a light dependent resistor called?

  It is called an LDR.
• How does the resistance of an LDR change in light conditions?

  The resistance is low in light.
• How does the resistance of an LDR change in dark conditions?

  The resistance is high in darkness.
• What is the relationship between current and potential difference in an ohmic conductor?

  Current is directly proportional to potential difference.
• What happens to the current through a resistor when the temperature is constant?

  The current remains directly proportional to potential difference.
• What is the symbol for a resistor?

  It is a zigzag line.
• What is the function of an LDR in circuits?

  It detects light levels.
• How does an LDR work in a mobile phone?

  It turns off the screen when near the ear.
• What is the basic operation of an LDR in a circuit?

  • High resistance in darkness
  • Low resistance in light
  • Used to control devices based on light
• What happens to the potential difference across an LDR in light?

  The potential difference is low.
• What happens to the potential difference across an LDR in darkness?

  The potential difference is high.
• What is the effect of high resistance in an LDR on a lamp in a circuit?

  The lamp becomes very dim.
• How do garden lamps utilize LDRs?

  They turn on in darkness and off in light.
• What are the key features of an LDR's operation in a circuit?

  • High resistance in dark conditions
  • Low resistance in light conditions
  • Used to control devices based on light
• How does the potential difference across the lamp change when the phone is held to the ear?

  The potential difference across the lamp is low.