1. 

In an intrinsic semiconductor, the number of free electrons

A. Equals the number of holes
B. Is less than the number of holes
C. Is greater than the number of holes
D. Impossible to say

2. 

A device that converts mechanical into electrical energy is?

A. solar cell
B. thermocouple
C. chemical cell
D. generator

3. 

Which one of the following kinds of materials has the lowest permeability?

A. A diamagnetic material
B. A paramagnetic material
C. A feiTomagnetic material
D. All of the above

4. 

The total impedance of a parallel RLC circuit:

A. always increases as the applied frequency increases
B. is equal to the sum of the values of resistance, inductive reactance and capacitive reactance
C. always decreases as the applied frequency increases
D. is maximum at the resonant frequency

5. 

The rise time of a pulse waveform is the time required for the voltage to rise:

A. from zero to its rms value
B. from zero to its peak value
C. from 10% of the peak value to 70.7% of the peak value
D. from 10% of the peak value to 90% of the peak value