A sound wave is sampled and the amplitude of each sample is stored using 2 bits.
Identify the number of different amplitude values that can be stored for each sample.
Mark scheme
- B 4 (1)
- The only correct answer is B. The correct answer is 4 (2 bits give 2^2 = 4 values).
- A is not correct because 2 is the number of bits used to store each sample
- C is not correct because 8 different amplitude values would need 3 bits
- D is not correct because 16 different amplitude values would need 4 bits
Example answers and how they were marked
Full marks1/1
B 4
Why: Selects the only correct option (1).
No marks0/1
C 8
Why: Near miss: 8 values would need 3 bits, one more than this recording uses (0).
No marks0/1
A 2
Why: Typical misconception: 2 is the number of bits, not the number of amplitude values those bits can store (0).