Filters in Electrical Engineering MCQ Questions

Contents

- 1 The bandwidth of an ideal low-pass filter
- 2 The number of poles in a low pass active filter indicates
- 3 If fc1 and fc2 are lower and upper critical frequencies respectively, then bandwidth of a band pass filter is mathematically expressed in the form
- 4 If fc1 and fc2 are lower and upper critical frequencies and fo is center frequency, then which of following is correct formula to calculate center frequency
- 5 Quality factor and Damping factor in a band pass filter are related as

## The bandwidth of an ideal low-pass filter

The bandwidth of an ideal low-pass filter:

- Is more than critical frequency
- Is equal to critical frequency
- Is less than critical frequency

Correct answer: 2. Is equal to critical frequency

Explanation: In an ideal low pass filter, the critical frequency sometimes also known the *cutoff frequency*) defines the end of the passband and is normally specified at the point where the response drops (70.7%) from the passband response. The bandwidth of an ideal low-pass filter is equal to critical frequency fc.

Mathematically,

BW = fc

## The number of poles in a low pass active filter indicates

The number of poles in a low pass active filter indicates:

- Number of RC circuits in filter
- Number of resistors in filter
- Number of capacitors in filter
- Number of inductors in filter

Correct answer: 1. Number of RC circuits in filter

## If fc1 and fc2 are lower and upper critical frequencies respectively, then bandwidth of a band pass filter is mathematically expressed in the form

If fc1 and fc2 are lower and upper critical frequencies respectively, then bandwidth of a bandpass filter is mathematically expressed in the form:

- BW = fc1 – fc2
- BW = fc2 – fc1
- BW = fc1 + fc2
- BW = fc2 * fc1

Correct answer: 2. BW = fc2 – fc1

## If fc1 and fc2 are lower and upper critical frequencies and fo is center frequency, then which of following is correct formula to calculate center frequency

If fc1 and fc2 are lower and upper critical frequencies and fo is center frequency, then which of following is correct formula to calculate center frequency:

- fo = √(fc1 + fc2)
- fo = √(fc1 – fc2)
- fo = 1/√(fc1 * fc2)
- fo = √(fc1 * fc2)

Correct answer: 4. fo = √(fc1 * fc2)

Quality factor and Damping factor in a band pass filter are related as:

- Q ∝ DF
- Q = 1/DF
- Q + DF = 3.5
- None of above

Correct answer: 2. Q = 1/DF