3272-3 ELEC (3.4)

A load that is subject to a potential difference with a current running through it will. have a magnetic field around it with the magnitude and direction of the field determined by the corkscrew rule. dissipate power in the form of heat. will move in a direction shown by the right hand rule.

In a Desynn indicator system, the rotor is. an electromagnet. a permanent magnet. an AC magnet.

Which is not thermally operated?. A limiting resistor. A current limiter. A fuse.

In a series circuit with 3 resistors, the current is. lower than the smallest. the total of all 3 using ohms law to find the current. even in all 3.

To find the internal resistance of a battery in a circuit of known current. use the formula R = V * I. find the lost volts of the circuit. find the emf of the circuit.

A parallel circuit with any number of 2 terminal connections. the individual voltage drops is equal to the emf. has the same current throughout. the resistance is dependent on current.

A 24V battery has an internal resistance of 1 ohm. When connected to a load, 12 amps flows. The value of the load is. 12 ohms. 1/2 ohm. 1 ohm.

In a balanced Wheatstone bridge, across the centre of the bridge there is. current and voltage at maximum. no current flow. no voltage present at either end.

An ammeter is connected into a circuit in. series. shunt. parallel.

In a series resistive circuit. the total voltage is equal to the sum of the individual voltages. the total voltage is the same as the highest individual. the total voltage equals the difference between the individual voltages.

In a circuit containing three resistors of equal value connected in series and one of the resistors short circuits, the effect is for the current in the other two resistors to. decrease. increase. remain the same.

In general, increasing the cross sectional area of an electrical cable. increases its resistance. enables it to carry more voltage. enables it to carry more current.

In a Wheatstone Bridge, the ammeter reads zero, and the variable resistor is adjusted to 5 ohms. Resistor P has a value of 10 ohms and Q has a value of 100 ohms. What is the value of the unknown resistor?. 5 ohms. 0.5 ohms. 50 ohms.

Potentiometers are used as a. variable voltage source. variable resistor. variable current source.

If the resistance of a resistor which is in series with two other resistors is doubled. the current in that resistance is doubled. the volts drop across that resistor increases. the current in that resistance is halved.

Total resistance in a parallel resistor circuit, of R1 and R2 is. RT = 1/R1 + 1/R2. 1/RT = (R1 * R2) ÷ (R1 + R2). 1/RT = 1/R1 + 1/R2.

Small resistors too small or mis-shapen for the application of colour are marked instead using. an abbreviated resistance value. a letter code. a dot code.

The electron flow through a conductor will be decreased the most if the cross sectional area. is decreased and the length is increased. and the length are both decreased. and the length are both increased.

A resistor has 4 bands on it coloured blue, yellow, yellow, gold. It`s value is. 640 kohm ± 5%. 4 mohm ± 10%. 64 kohm ± 5%.

Resistance is measured using what unit of temperature?. Absolute. Centigrade. Fahrenheit.

The resistance of a material is. independent of the material type. the same as its conductance. the reciprocal of its conductance.

A 47 kilohm resistor has the following colour code: Yellow, Violet, Orange. Red, Orange, Yellow. Orange, Violet, Red.

If 2 resistors, one red, yellow, black, gold and the other violet, blue, black, silver were replaced by a single resistor. Ignoring tolerance, what would the colour coding be?. Brown, black, brown. Black, brown, black. Brown, black, black.

Which of these will cause the resistance of a conductor to decrease?. Decrease the length or the cross-sectional area. Increase the length or decrease the cross-sectional area. Decrease the length or increase the cross-sectional area.

When resistors are in parallel the total current is equal to. the current through one resistor. the sum of the currents. the reciprocal of all the currents.

The resistance to electrical flow in a wire depends on. the diameter, length, material of wire and temperature. the material only - copper or aluminium. the length and material of the wire only.

If a number of resistors are connected in parallel, the total resistance is. smaller than the lowest. the same as the lowest. greater than the lowest.

What is the combined value of resistances of 4 ohm and 6 ohm connected in parallel?. 2.4 ohm. 0.24 ohm. 24 ohm.

The formula for resistance in series is. RT = R1 + R2 + R3 + ... + Rn. RT = R1 * R2 * R3 * ... * Rn. 1/RT = 1/( R1 * R2 * R3 * ... * Rn).

A potentiometer varies. resistance. current. voltage.

Six resistors each of 6 ohms would be. 1 ohm in series. 1 ohm in parallel. 36 ohms in parallel.

The total resistance in a circuit is greater than the least resistor. This is true for a. series and parallel circuit. series circuit only. parallel circuit only.

A 47 Kilohm resistor with a 10% tolerance has the following colour code: Yellow, Violet, Orange, Silver. Orange, Violet, Red, Gold. Red, Orange, Yellow, Silver.

The unit for resistivity is the. ohms/square meter. ohms/meter. ohm. meter.

In a Wheatstone bridge at balance the galvanometer reads zero. amps. ohms. volts.

A 2 Megohm resistor can be written. 2M0F. 20MF. M20F.

When light hits a photodiode, its resistance. stays the same. increases. decreases.

Conductance of a circuit is 2 milliMhos. What is its resistance?. 5000 Ohms. 500 Ohms. 5 Megohms.

Five different value resistors all have the same voltage dropped across them. How are the resistors connected?. In Series/Parallel. In Series. In Parallel.

In a parallel circuit containing resistors. the sum of the voltage drops equals applied voltage. the voltage is the same in all parts of the circuit. resistance is determined by value of current flow.

A 300 ohm resistor would have a colour code of. orange, black, brown. orange, orange, brown. orange, brown, black.

A thyristor. if energized on, will switch on a circuit. has a positive temperature coefficient. if energized on, will switch off a circuit.

If a resistor is too small or misshapen to fit the colour code bands, how else is it`s value indicated?. Dots. Number code. Letter code.

If the temperature of a pure metal is reduced to absolute zero, its resistance will be. unaffected. practically zero. infinity.

The 5th coloured band on a resistor represents the. reliability or temperature coefficient. tolerance. multiplier.

Carbon has a. temperature coefficient of zero. positive temperature coefficient. negative temperature coefficient.

What happens to the resistance of a copper conductor when the temperature increases?. It decreases. It increases. It remains the same.

Copper is an inferior conductor to aluminium when comparing. CSA with CSA. weight for weight. load for load.

An increase in operating temperature in most electrical devices carrying current results in. a decrease in resistance and an increase in current. no effect on the resistance and current. an increase in resistance and a decrease in current.

A potentiometer has which of the following properties?. Wire wound. 3 terminals. Preset values.

A 3 ohm resistor dissipates 27 Watts. How much current flows through it?. 9 A. 15 A. 3 A.

A 500 ohm resistor carries a 3 amp current. What is the power dissipated?. 500 W. 4.5 kW. 5 kW.

The power in a circuit when voltage and resistance is given can be found by. V*R. V*V*R. V*V / R.

Power is the rate of doing work. It is measured in. joules/second. joules * seconds. watts/second.

A DC circuit containing a total resistance of 100 ohms has a current flow of 250 mA. The power dissipated in the circuit is. 6.25 watts. 5 watts. 0.4 watts.

What is the power dissipated in a 500 ohm resistor with a 3A flow?. 1.5 kW. 4.5 kW. 750 kW.

The earth lead of a 24 V equipment is 0.5 ohm resistance and carries 80 A. How much power does it dissipate?. 1.152 kW. 1.92 kW. 3.2 kW.

A resistor dissipates 80 Watts. If it runs for 4 hours 15 minutes, how much energy is dissipated in total?. 1.224 MJ. 4 kJ. 191.

A 10 V battery supplies a resistive load of 10 ohms for 1 minute. What is the power supplied?. 100 W. 10 VA. 10 W.

237) The temperature of a pure metal can greatly affect the resistance of it. What temperature scale is used?. Absolute. Centigrade. Fahrenheit.

A piece of equipment is rated at 750 watts and the applied voltage is 30 volts. The value of the protection fuse should be. 20 amps. 15 amps. 30 amps.

A 48-volt direct current source is required to furnish 192 watts to a parallel circuit consisting of three resistors of equal value. What is the value of each resistor?. 12 ohm. 36 ohm. 4 ohm.