Photo Transistor Concepts and Applications

The video introduces photo transistors, explaining their function as semiconductor devices that convert light into current. It covers their construction, highlighting the large base and collector areas for increased current generation. The working principle is detailed, showing how light affects the base current and collector current. Advantages include high efficiency and low cost, while disadvantages involve poor performance at high frequencies. Applications range from counting systems to printers.

What is the primary function of a photo transistor?

• To convert light into heat

• To convert light into photo current

• To convert current into light

• To convert heat into current

Which terminals does the current flow through in a photo transistor?

• Emitter and Collector

• Base and Collector

• Collector and Base

• Emitter and Base

What is the symbol of a photo transistor similar to?

• Capacitor

• Diode

• Resistor

• Transistor

What is the purpose of increasing the base area in a photo transistor?

• To reduce the current generated

• To increase the amount of current generated

• To decrease the light absorption

• To reduce the size of the device

What materials are recently used to make photo transistors for higher efficiency?

• Silicon and Germanium

• Iron and Nickel

• Gallium and Arsenic

• Copper and Zinc

What happens when no light is incident on the base terminal of a photo transistor?

• Base current is generated

• Maximum current flows

• Only leakage current flows

• No current flows

What is the relationship between collector current and the intensity of incident light in a photo transistor?

• Collector current decreases with intensity

• Collector current remains constant

• Collector current increases with intensity

• Collector current is independent of intensity

Which of the following is NOT an advantage of photo transistors?

• High cost

• Faster response

• Less noise interference

• High efficiency

Which application is NOT associated with photo transistors?

• Optical tape readers

• Generating electricity

• Counting systems

• Detecting objects

What is a disadvantage of photo transistors compared to photodiodes?

• Larger size

• Poor performance at high frequency

• More noise interference

• Higher cost