Electronics and Communication Systems Lecture Review

Comprehensive practice questions covering oscillators, transmission lines, power supplies, digital modulation, and basic electromagnetism based on the lecture transcript.

What type of feedback does an oscillator employ?

Positive feedback

In a phase shift oscillator, what are the frequency determining elements?

R and C

How is feedback obtained in a Colpitt’s oscillator?

From the centre of split capacitors

What is an example of an unbalanced line?

A coaxial cable

The velocity factor of a cable depends mostly on which factor?

The dielectric constant

What is the optimum value for Standed Wave Ratio (SWR)?

One

What is a Smith Chart used to calculate?

Transmission line impedances

A regulator has a no-load voltage of $6\,V$ and a full-load output of $5.82\,V$. What is its load regulation?

$$3.09\%$$

What is the voltage regulation of an ideal regulated power supply?

$$0\%$$

In an unregulated power supply, what happens to the output voltage if the load current increases?

It decreases

How is the turns ratio of a transformer defined?

The ratio of the primary voltage to the secondary voltage

A transformer has a turns ratio of $1:5$. If the primary voltage is $120\,\text{volts}$, what is the secondary voltage?

$$600\,\text{volts}$$

How many different phase angles does QPSK use?

4

What formula represents the Shannon Limit?

$$C = B \log_{2}(1 + S/N)$$

Why is companding used in digital transmission?

To preserve dynamic range while keeping bit-rate low

What is the majority carrier on the base in an npn transistor?

Hole

In an R-L-C circuit, what is the Form Factor ratio?

r.m.s. value / average value

What is the power factor of a D.C. circuit?

Unity

Where is the force strongest on a magnet?

Both poles of the magnet

What situation can create a magnetic field?

Moving electric charges