##### BOARD DIPLOMA EXAMINATIONS, (C-14)

DEEE-THIRD SEMISTER EXAMINATIONS

MODEL PAPER-II

ELECTRICAL CIRCUITS

SUB CODE:EE-303

##### Time: 3 Hours Total marks: 80

###### PART-A 10 X 3=30

**Instructions: 1) Answer all questions.**

**2) Each answer carries three marks.**

**3) Answer should be brief and straight to the point and shall not exceed**

**five simple sentences.**

- Define junction, branch and loop in circuits.
- State the limitations of ohm’s law.
- Define (a) cycle (b) time period (c) frequency.
- Convert the polar form 100 /͟30° into rectangular form.
- Define RMS value and average value.
- A pure inductance coil taken a current of 15 amps for 200volts, 50 Hz, AC Supply find the inductance of the coil.
- Define resonance and write the formula for the resonant frequency for RLC series circuit.
- Why a parallel resonant circuit is called a rejecter circuit.
- List the advantages of poly phase system over single phase system.
- State the relation between line voltage and phase voltage, line current and phase current in delta connected network.

**PART-B 5 X 10=50**

**Instructions: 1) Answer any five questions.**

**2) Each answer carries ten marks.**

- Two batteries E1 and E2 have emf’s 6 volts and 2volts respectively and external resistances of 2 ohms and 3 ohm respectively are connected in parallel across 5 ohms resistor. Calculate (a) the current in each of the battery (b) the potential difference across 5ohms resistor.
- Derive the formula for delta to star transformation.
- State and explain about thevenens theorem.
- (a) Explain about phase and phase difference.

(b) A sine wave has a peak valve of 50 volts Determine

(i) RMS value (ii) Average value (iii) form factor.

- A resistance of 12 ohms, an inductance of 0.15 H and a capacitance of 100 micro farad are connected in series across a 100V, 50HZ, AC supply.

Calculate, (a) Impedance (b) current (c) power factor (d) power consumed.

- Draw and explain the graphical representation of series resonance and indicate the following in the graph.

(a) Resonant frequency (b) net reactance (c) impedance (d) current.

- (a) Define Q factor of a parallel resonant circuit.

(b) A coil of 20 ohms resistance and an inductance of 0.2H is connected in parallel with a condenser of 100 micro farad capacitance. Calculate the frequency at which the circuit will act as a non inductance resistance of “R”ohms.also find the value of “R”.

- Derive the formula for measurement of 3 phase power and power factor by using two watt meter method (balanced load).