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VashaNatasha [74]
3 years ago
7

An electric heater containing two heating wires X and Y is connected to a power supply of electromotive force(emf) 9.0V and negl

igible internal resistance as shown in fig 6.1
Wire X has a resistance of 2.4 ohm and wire Y has a resistance of 1.2ohm. A voltmeter is connected in parallel with the wires. A variable resistor is used to adjust the power dissipated in wires X and Y.

The variable resistor is adjusted so that the voltmeter reads 6.0V.

Calculate the resistance of the variable resistor. ​

Physics
1 answer:
mina [271]3 years ago
7 0

Answer:

0.4 ohms.

Explanation:

From the circuit,

The voltage reading in the voltmeter = voltage drop across each of the parallel resistance.

1/R' = 1/R1+1/R2

R' = (R1×R2)/(R1+R2)

R' = (2.4×1.2)/(2.4+1.2)

R' = 2.88/3.6

R' = 0.8 ohms.

Hence the current flowing through the circuit is

I = V'/R'................ Equation 1

Where V' = voltmeter reading

I = 6/0.8

I = 7.5 A

This is the same current that flows through the variable resistor.

Voltage drop across the variable resistor = 9-6 = 3 V

Therefore, the resistance of the variable resistor = 3/7.5

Resistance = 0.4 ohms.

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Anyone know the answer to this question?
nikitadnepr [17]

- The integers 1,2,3,4,5,6,7,8,9 are always significant

- Zeros in between numbers are always significant

Explanation:

The rules to determine whether a digit is significant or not are the following:

- All the non-zero digits are significant: 1,2,3,4,5,6,7,8,9

- The zeros between two non-zero numbers are always significant

- The zeros before non-zero numbers on the left of the decimal point are never significant

- The zeros given after a non-zero number on the right of the decimal point are significant if they provide information about the precision of the measure

So now let's analyze the statements given:

- The integers 1,2,3,4,5,6,7,8,9 are always significant --> true

- All numbers to the right of the decimal point are always significant --> false. For instance, in 0.012, only 1 and 2 are significant.

- Zeros to the left of a decimal point and in a number greater than or equal to 10 are always significant --> false. For instance, in 7200, the two zeros are not significant.

- All zeros are significant numbers --> false, as we saw in the previous examples

- Zeros in between numbers are alwasy significant --> true

Learn more about significant figures here:

brainly.com/question/5028090

#LearnwithBrainly

4 0
3 years ago
SHOW ADEQUATE WORKINGS IN THIS SECTION
cluponka [151]

Answer:

12 i. The work done by Wale = 107.910 kJ

The work done by Lekan = 117.720 kJ

Total work done = 225.36 kJ

ii. Wale's power =  4.3164 kW

Lekan's power = 3.924 kW

Wale has more power and is more powerful than Lekan

13. 313.92 N

Explanation:

i. The work done, W = Force, F × Distance moved by the force, D

The given parameters are

The mass of Wale = 55 kg

The mass of Lekan = 60 kg

The acceleration due to gravity, g =9.81 m/s²

The motion force of Wale and Lekan are;

Motion force of Wale = 9.81 × 55 = 539.55 N

Motion force of Lekan = 9.81 × 60 = 588.6 N

The work done by Wale = 539.55 × 200 = 107910 J = 107.910 kJ

The work done by Lekan= 588.6 × 200 = 117720 J = 117.720 kJ

107910 + 117720 =225630 J = 225.36 kJ

ii. Power = Work done/time

Wale finished the race in 25 s, therefore, his power = 107910/25 = 4316.4 W

Lekan finished the race in 30 s, therefore, his power = 117720/30 = 3924 W

Wale has more power and is more powerful than Lekan

13. The velocity ratio = 5

V. R. = Distance moved by effort/(Distance moved by load)

Efficiency = 80%

Work done by effort = x

Work done by machine = Efficiency × Work done by effort  = 0.8 × x

Distance moved by effort, E = V. R. × Distance moved by load, D = 5 × D

Work done by effort = Force × Distance moved = 200×9.81× E

Work done by effort = 1962×E = 1962×E = 1962×5×D

Work done by machine = 1962 × D, when D = 1, we have;

0.8 × 1962×1 = 1569.6 J

Work done by effort = Force × Distance moved

Work done by effort = Force × 5×D = Force × 5 (D = 1)

From the principle of conservation of energy, we have;

Energy is neither created nor destroyed

Therefore

Work done by effort = Force × 5 = 1569.6 J

Force = 1569.6 /5 = 313.92 N.

3 0
3 years ago
How do waves shape Earth’s surface? HELP PLS 10 POINTS PLUS BRAINLEST
Leto [7]

Answer:Waves shape the earths surface because they change the form of the coastal land form, meaning that when a wave is formed and moves they are also moving sand and rocks which can change the shape of the surface

Explanation:

6 0
3 years ago
When cattle are processed, what is the most likely use for the animals' skin?
galben [10]

When cattle are processed, the most likely use for the animals' skin is in

the production of Leather.

<h3 /><h3>Animals used for Leather production</h3>
  • Cattle
  • Goat
  • Crocodile etc.

The commonly used animals in leather production is however cattle and

they amount for a large percentage of leather present today. They also

involve various techniques such as tanning and crusting to ensure

conversion to leather.

Read more about Leather here brainly.com/question/2494725

3 0
2 years ago
Determine the ratio of the resistivity of pure water to silver?
shutvik [7]
Silver is a very good conductor, this means its resistivity is very low (from table, we can check the precise value, which is \rho_s = 1.6 \cdot 10^{-8} \Omega m).

Pure water, instead, is a very bad conductor, this means its resistivity is very high, of order of k \Omega \cdot m (10^3 \Omega m ). Even without knowing the precise value of the pure water resistivity, we can estimate the ratio between the pure water resistivity and the silver resistivity by comparing the two orders of magnitude:
r= \frac{10^3 \Omega m}{10^{-8} \Omega m}  \sim 10^{11}

Therefore, we can say that the correct answer is
3 \cdot 10^{11} : 1
3 0
3 years ago
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