Transistors

In which circuit does the bulb light up?

• 
• 
• 
• 

What are the names of the terminals X, Y and Z?

• X = Base, Y = Collector, Z = Emitter

• X = Emitter, Y = Base, Z = Collector

• X = Collector, Y = Base, Z = Emitter

• X = Collector, Y = Emitter, Z = Base

Diagram shows an automatic switch circuit to light up a bulb during the day time. What changes should be done to light up the bulb at night?

• Interchange R₁ and R₃

• Reverse the terminal of the battery

• Replace the npn transistor with a pnp transistor

• Interchange R₁ and the LDR

Diagram shows a light controlled switch. The alarm will be activated when

• the surrounding is dark

• the surrounding is bright

• the temperature of the surrounding is high

• the temperature of the surrounding is low

The street lights use electronic control system that switches the lights on when the surrounding is dark. What is the input sensor of the control system?

• A thermistor

• A light emitting diode

• A microphone

• A light dependent resistor