Multiple choice

Consider the following statements regarding Photo-resistors: (a) Special semiconductor crystal, such as cadmium sulfide or Copper sulfide is used to make photo-resistors (b) When this semiconductor is placed in light, electrons within its structure resist flow through the resistor because they are too strongly bound to the crystal’s atoms (c) Liberated holes contribute to the current flowing through the device Which of the above statements is/are wrong?

  1. Only (a) and (c)

  2. Only (a) and (b)

  3. Only (b) and (c)

  4. All the above

  5. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Statement (a) is wrong. Special semiconductor crystal, such as cadmium sulfide or lead sulfide is used to make photo-resistors. Statement (b) is also wrong. When this semiconductor is placed in dark, electrons within its structure resist flow through the resistor because they are too strongly bound to the crystal’s atoms. Statement (c) is also wrong. Liberated electrons contribute to the current flowing through the device.

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