Electrical Scientific Principles 202

What Is The Frequency used In The UK

• 50hz

• 60hz

• 55hz

• 70hz

Answer explanation

The standard frequency for electrical power in the UK is 50Hz. This is the frequency at which alternating current (AC) is generated and used in homes and businesses.

Tags

Frequency

What current is produced if we have a 230v supply with an appliance of 1500w?

• 1000A

• 2.9A

• 6.5A

• 13A

Answer explanation

To find the current, use the formula: Current (I) = Power (P) / Voltage (V). Here, I = 1500W / 230V = 6.5A. Thus, the correct answer is 6.5A.

Tags

Power Triangles

What size conductor is typically used for sockets in a domestic dwelling?

• 1.5mm

• 2.5mm

• 4mm

• 0.75mm

Answer explanation

In domestic wiring, 2.5mm conductors are typically used for socket outlets to handle the required current safely. Smaller sizes like 1.5mm or 0.75mm are insufficient for this purpose, while 4mm is generally used for higher loads.

Tags

General

If we have a motor with 50% efficiency but at 100% efficiency needs 3KW, What power will it draw?

• 3Kw

• 2Kw

• 2.5Kw

• 6Kw

Answer explanation

The motor operates at 50% efficiency, meaning it only uses half the power effectively. To find the power drawn, divide the required power (3KW) by the efficiency (0.5): 3KW / 0.5 = 6KW. Thus, the motor will draw 6KW.

Tags

Motors

What frequencies are most electrical items made to be compatible with?

• 50hz

• 60hz

• 55hz

• 65hz

Answer explanation

Most electrical items are designed to operate at either 50Hz or 60Hz, which are the standard frequencies used in different regions worldwide. Therefore, the correct answers are 50Hz and 60Hz.

Tags

Frequency

What is the correct formulas for calculating amperes?

Answer explanation

The correct formulas for calculating amperes are derived from Ohm's Law and the power formula. V/R gives current (I), and P/V also gives current when rearranged. Thus, V/R and P/V are correct for calculating amperes.

Tags

Power Triangles

What is one effect caused by electrical current?

(a)  

Answer explanation

One effect caused by electrical current is thermal energy, which is produced when current flows through a conductor, generating heat due to resistance. This is known as the Joule heating effect.

Tags

General

What potential is produced across a resistance of 15 ohms if a current of 12 amperes are flowing through it?

• 230V

• 240V

• 200V

• 180V

Answer explanation

To find the potential across a resistance, use Ohm's Law: V = I × R. Here, I = 12 A and R = 15 Ω. Thus, V = 12 × 15 = 180V. Therefore, the correct answer is 180V.

Tags

Power Triangles

What is the current flowing in the circuit when 198 volts is present across a resistance of 3.3 ohms?

• 50A

• 57A

• 60A

• 59A

Answer explanation

Using Ohm's Law (I = V/R), the current I is calculated as I = 198V / 3.3Ω = 60A. Therefore, the correct answer is 60A.

Tags

Power Triangles

Four resistors in series have a voltage drop across them of 37V, 55V, 29V & 119V calculate the supply voltage.

• 230V

• 250V

• 240V

• 300V

Answer explanation

To find the supply voltage, sum the voltage drops: 37V + 55V + 29V + 119V = 240V. Therefore, the supply voltage is 240V.

Tags

Resistors