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2C : esistors checkpoints


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CHECKPOINT A

1. List three ways in which resistors are used in circuits.

2. What is a transducer?

3. Give examples of input and output transducers.

to ANSWERS A Back

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CHECKPOINT B

1. List three different manufactured types of resistor,

2. What resistor values are indicated by the following colour bands?

(A) brown, black, red
(B) grey, red, brown
(C) orange, white, green

3. What are the colour codes for the following resistance values?

(A) 1.8 kW
(B) 270 W
(C) 56 kW

4. What are the maximum and minimum values of a resistor with a nominal value of 220 W, marked with a gold tolerance band?

to ANSWERS B Back

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CHECKPOINT C

1. What resistor values are indicated by the following colour bands?

(A) orange, orange, black
(B) grey, red, gold
(C) orange, orange, black, red

2. What is the colour code for a 10 kW resistor

(A) using the three colour system?
(B) using the four colour system?

to ANSWERS C Back

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CHECKPOINT D

1. Which E12 value is closest to 5 030 W?

to ANSWERS D Back

 


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CHECKPOINT E

1. In the circuit for lighting an LED, the power supply is changed to 6 V:

What should be the new value for R1?

to ANSWERS E Back

 


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CHECKPOINT F

1. In the circuit below:

what is

(A) the total resistance in the circuit?
(B) the current flowing at point A?

2. In the circuit below:

what is

(A) the total resistance in the circuit?
(B) the current flowing at points B, C, and D?

to ANSWERS F Back

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CHECKPOINT G

1. Which power rating of resistor is required for a 680 W current limiting resistor in series with an LED if the current flowing is 10 mA?

to ANSWERS G Back

 


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ANSWERS A

1. To limit current, with a transducer as part of a sensor subsystem, with a capacitor to introduce a time delay.

2. A component which changes one form of energy into another, where one of the forms of energy is electrical.

3. Input: LDR, microphone, switch, thermistor (temperature sensitive) Output: LED, lamp, loudspeaker, buzzer.

back to CHECKPOINT A


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ANSWERS B

1. Carbon film, metal film, wirewound.

2. Resistor values:

(A) 1000 W, or 1 kW
(B) 820 W
(C) 3 900 000 W, or 3.9 MW.

3. Colour codes:

(A) brown, grey, red
(B) red, violet, brown
(C) green, blue, orange

4. Gold = 5% maximum: 220+11=231 W minimum: 220-11=209 W

back to CHECKPOINT B


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ANSWERS C

1. Resistor values:

(A) 33 W
(B) 8.2 W
(C) 33 000 W, or 33 kW

2. Colour codes:

(A) brown, black, orange
(B) brown, black, black, red

back to CHECKPOINT C


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ANSWERS D

1. E12 values of 4.7 kW and 56 kW are available: 4.7 kW is closer. On the E24 scale, 5.1 kW is closest.

back to CHECKPOINT D


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ANSWERS E

1. The voltage across R1 is now 6-4=2 V

The closest E12 value is 390 W, colour code orange, white, brown.

back to CHECKPOINT E


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ANSWERS F

1. Resistors in series:

(A) 3 kW
(B) 2 mA

2. Resistors in parallel:

(A) 0.67 kW
(B) B=9 mA, C=6 mA, D=3 mA

The resistors connected in parallel have different values and it follows that the currents flowing through them will be different.

back to CHECKPOINT F


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ANSWERS G

1. 10 mA=0.01 A. The voltage across the 680 W is:

The power is:

Any resistor of a higher rating will do, either 0.25 W or 0.5 W.

back to CHECKPOINT G


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