Which device is a semiconductor that allows current to flow in only one direction?

Which device is a semiconductor that allows current to flow in only one direction?

• A. Diode
• B. Friction
• C. Ohmic
• D. LDR

Answer: (A)

A diode is a semiconductor device that conducts current in only one direction because of its p-n junction. When the anode is more positive than the cathode (forward bias), the depletion region narrows and charge carriers can cross, so current flows. If the polarity is reversed (reverse bias), the depletion region widens and very little current can pass, so the current is effectively blocked. This one-way conduction is why a diode is used to control the direction of current in circuits. Other options don’t fit this role: friction produces static electricity but isn’t a controlled conduction path; an Ohmic device like a resistor follows Ohm’s law and does not restrict current to one direction; a light-dependent resistor changes its resistance with light, not the direction of current.

A diode is a semiconductor device that conducts current in only one direction because of its p-n junction. When the anode is more positive than the cathode (forward bias), the depletion region narrows and charge carriers can cross, so current flows. If the polarity is reversed (reverse bias), the depletion region widens and very little current can pass, so the current is effectively blocked. This one-way conduction is why a diode is used to control the direction of current in circuits.

Other options don’t fit this role: friction produces static electricity but isn’t a controlled conduction path; an Ohmic device like a resistor follows Ohm’s law and does not restrict current to one direction; a light-dependent resistor changes its resistance with light, not the direction of current.