ISRO Scientist/Engineer EE Solved Papers

A transformer secondary is connected to pure resistive load. The power factor on the primary side will be

When one transformer is removed from a delta-delta bank of a 30 kVA transformer, the capacity of the resulting 3-phase transformer in V-V connection will be

In an auto-transformer, power is transferred through

A 3-phase induction motor is applied with a 400 V, 50 Hz supply and the motor runs at 1470 rpm. The rotor current will have a frequency of

A DC shunt motor is running at 1200 rpm, when excited with 220V DC. Neglecting the losses and saturation, the speed of the motor when connected to a 175 V DC supply is

The electric field intensity at a point situated 4 metres from a point charge is 200 N/C. If the distance is reduced to 2 metres, the field intensity will be

A capacitor consists of two metal plates each $500\times500\text{ mm}^2$ and spaced 6 mm apart. The space between the metal plates is filled with a glass plate of 4 mm thickness and of paper of 2 mm thickness. The relative permittivity's of the glass and paper are 8 and 2 respectively. Neglecting the fringing effect, the capacitance will be (permittivity of the free $\text{space}=8.85\times10^{-12}\text{ F/m}$)

A hollow metallic sphere of radius r is kept at potential of 1 volt. The total electric flux coming out of the concentric spherical surface of radius R (>r) is

A solid iron cylinder is placed in a region containing a uniform magnetic field such that the cylinder axis is parallel to the magnetic field direction. The magnetic field lines inside the cylinder will

The pressure coil of a dynamometer type wattmeter is

A metal has strain gauge factor of two. Its nominal resistance is 120 ohms. If it undergoes a strain of 10-5, the value of change of resistance in response to the strain is

A d.c. voltmeter has a sensitivity of 1000 ohm/Volt. When it measures half full scale in 100 V range, the current through the voltmeter will be

A 230 V, 10 A, single phase energy meter makes 90 revolutions in 3 minutes at half load rated voltage and unity pf. If the meter constant is 1800 rev/kWh, then its error at half load will be

Wavelength of which material is considered for defining the standard metre

The current flowing through the resistor $R=100\pm0.3\%\,\Omega$ is $I=2\pm4\%\text{ A}$ The limiting error in the power dissipation in the resistor R is

A 0 to 150 V voltmeter has an error of $\pm2\%$ of full-scale deflection. What is the range of readings if true voltage is 50 V?

The input impedance of CRO is approximately

Which of the following measurements cannot be made with the help of a frequency counter?

A 10 bit A/D converter is used to digitise an analog signal in the 0 to 5 V range. The maximum peak to ripple voltage that can be allowed in the D.C. supply voltage is

The Latching current of SCR is 18 mA. Its holding current will be

A single-phase half-wave controlled rectifier has 400sin(314t) as the input voltage and R as the load. For the firing angle of 60 deg for the SCR, the average output voltage is

The turn-on time of a SCR with inductive load is 20 micro seconds. The pulse train is 2.5 kHz with a mark/space ratio of 1/10, then the SCR will

In an inverter with fundamental output frequency of 50 Hz, if third harmonic is eliminated, then frequencies in Hz of other components in the output voltage would be

In the single-phase voltage controller circuit shown in figure below, for what range of triggering angle (a), the output voltage (Vo) is not controllable?

In a diode, the reverse recovery time is defined as the time between the instant diode current becomes zero and the instant reverse recovery current decays to