Ask a question about the relationship between electrical power and resistance

P=UI: The power delivered is 50kW=50000W, and the output voltage is 1500V

Then the delivery current is i=p u=50000 1500=100 3 a, and the resistance on the line is r0

Then the power on the line is p1=i r0=(100 3) r0=10000 w

Solve r0=9 beating.

If it is delivered at 4500V, the current i1=p u1=50000 4500=10 9 A

The power lost on the line is p2=i1 r0=(10 9) r0=100 9 w

If it is conveyed at 4500V, the loss can be reduced to p=p1-p2=

Calculate the current i on the line first, according to the formula p=ui, the current is at 1500V.

i=50000 1500=100 3 amps.

Since the power loss at 1500V is known, the total resistance can be obtained according to the formula p=r*i 2.

r=10000 (100 3) 2=9 ohms.

If the power is transmitted at 4500V, the current is 50000 4500 = 100 9 amperes, and the power loss is 9 * (100 9) 2 = 1111 watts.

In a series circuit, the current is equal, the electrical power is proportional to the voltage, and the voltage is proportional to the resistance, so in a series circuit, the electrical power is proportional to the resistance.

In a parallel circuit, the voltage is equal, the electrical power is directly proportional to the current, and the current is inversely proportional to the resistance, so in a parallel circuit, the electrical power is inversely proportional to the resistance.

When discussing the relationship between electrical power and resistance, it is important to distinguish between series and parallel circuits!

Expressed in a formula:

In a series circuit, p=iu=i 2r.

In parallel circuits, p=iu=u2 r.

The relationship between electrical power and resistance is: w = q = i 2rt, a pure resistance circuit formula, the power is proportional to the square of the resistance and the current.

If the voltage is constant, p=U2 R, the electrical power is inversely proportional to the resistance; If the current is constant, p=i 2r, the electrical power is proportional to the resistance.

Electrical power The electrical power is equal to the voltage multiplied by the current: p=ui;

2.The electrical power is equal to the square of the current multiplied by the resistance: p=i 2*r (pure resistive circuit);

3.The electrical power is equal to the square of the voltage divided by the resistance: p = U2 r (pure resistance circuit);

It is derived from the formulas p=iu and i=u r: , which is derived from the premise that the current is certain (or the same), and when the resistance increases, the voltage must be increased to keep the current constant. So, the higher the resistance, the more power.

Namely:"Direct ratio. "When the resistance increases, keep the voltage constant, the current will inevitably decrease, and the power will also decrease.

Therefore, the greater the resistance, the smaller the power, i.e., the "inverse ratio".

Electrical power is a physical quantity that indicates how fast or slow an electric current is done, and the magnitude of the power of an electrical appliance is numerically equal to the amount of electrical energy it consumes in 1 second. If the electrical energy W (Si unit J) is consumed for such a long time as t (Si unit J), then the electrical power of this appliance is p=w t. The electrical power is also equal to the product of the voltage across the conductor and the current passing through the conductor.

The voltage at which the electrical appliance works normally is called the rated voltage, the power that the appliance works normally at the rated voltage is called the rated power, and the power at which the appliance works under the actual voltage is called the actual power.

Electrical power p. Electrical power is equal to voltage multiplied by current: p=ui; The electrical power is equal to the square of the current multiplied by the resistance:

p=i 2*r (pure resistive circuit); The electrical power is equal to the square of the voltage divided by the resistance: p = U2 r (pure resistance circuit); The electrical power is equal to the work divided by the time: p=w t.

Resistance is a physical quantity that describes the electrical conductivity of a conductor and is denoted by R. The resistance is defined by the ratio of the voltage u at both ends of the conductor to the current i passing through the conductor, i.e., r=u i. Therefore, when the voltage at both ends of the conductor is constant, the greater the resistance, the smaller the current passing through; Conversely, the smaller the resistance, the greater the current that will pass through.

Therefore, the magnitude of the resistance can be used to measure the strength of the conductor's resistance to the current, that is, the conductivity is good or bad. The amount of resistance is related to factors such as the material, shape, and volume of the conductor, as well as the surrounding environment.

The resistance of different conductors can be divided into two types according to their different properties. One is called linear resistance or ohmic resistance, which satisfies Ohm's law; The other type is called nonlinear resistance and does not satisfy Ohm's law. The reciprocal 1 r of the resistance is called the conductance and is also a physical quantity that describes the conductivity of a conductor and is denoted by g.

The unit of resistance in the International System of Units is the ohm ( ) referred to as the ohm. The International System of Units (SI) unit of conductance is Siemens (S), abbreviated as West. Resistance is also commonly used in units k and m, and the relationship between them is:

1mω=1000kω=1000000ω

Resistivity is a parameter that describes the electrical conductivity of a conductor. For a cylindrical homogeneous conductor made of a certain material, its resistance r is proportional to the length l and inversely proportional to the cross-sectional area s, i.e.:

where is the proportionality factor, which is determined by the material of the conductor and the ambient temperature, and is called resistivity. Its International System of Units (SI) is the ohm meter (·m). The relationship between resistivity and temperature of general metals at room temperature is:

ρ0（1+αt）。

1.Voltage = Current * Resistance, Voltage = Power Current.

2.Current = Voltage Resistance, Current = Power Voltage.

3.Resistance = voltage and current, resistance = square of voltage and power.

4.Power = square of voltage Resistance, Power = square of current * resistance, power = voltage * current.

5.Current: Scientifically the amount of electricity passing through any cross-section of a conductor per unit of time is called current intensity, referred to as current, the current symbol is i, the unit is ampere (a), referred to as ampere (Andre Marie Ampere, 1775-1836, French physicist and chemist, has made outstanding achievements in the research of electromagnetic interaction, and has also contributed to mathematics and physics.

6.The SI unit of electric current is named after its surname).

7.The free charge in the conductor moves regularly and directionally under the action of the electric field force to form an electric current.

8.Electrically stipulated: the direction of the directional flow of positive charge is the direction of the current.

9.In the project, the directional flow direction of the positive charge is the current direction, and the magnitude of the current is expressed by the charge q flowing through the conductor section per unit time, which is called the current intensity.

10.Nature has many kinds of carriers that carry electric charges, for example, electrons that can be moved in a conductor, ions in an electrolyte, electrons and ions in a plasma, quarks in hadrons.

11.The movement of these carriers forms an electric current.

Current (i), voltage (v), resistance (r) and power (p) are the basic concepts in electricity, and there are a series of relationships and calculation formulas between them.

1.Current (i): Current is the amount of charge passing through a conductor per unit of time and is measured in amperes (a).

2.Voltage (V): Voltage is the potential difference, which can also be understood as the energy enjoyed by the charge as it moves through the circuit, measured in volts (V).

3.Resistance (r): Resistance is the degree to which the flow of current is obstructed in a circuit and is measured in ohms ( ).

4.Power (P): Power is the conversion rate of electrical energy, that is, the energy consumed or produced in the mountains per hour, and the unit is watts (W).

The relationship between them can be calculated using the following formula:

Current vs. Voltage (Ohm's Law): U = i * R, where U is the voltage, I is the current, and R is the resistance.

Current vs. Resistance (Ohm's Law): i = u r, where i is the current, u is the voltage, and r is the resistance.

Voltage vs. Resistance (Ohm's Law): r = u i, where r is the electrical defense, u is the voltage, and i is the current.

Power and current, voltage relationship: p = i * v, where p is power, i is current, and v is voltage.

These relationships and formulas are very important in circuit analysis and design and can be used to calculate the interrelationships between voltage, current, resistance, and power. Depending on the situation, the above formulas can be used for calculations or other formulas can be used for derivation.

Derived from p=iu and i=u r:

When the current is constant, when the resistance increases, the voltage must be increased to keep the current constant. That is, the greater the resistance, the greater the power.

When the voltage is constant, when the resistance increases, in order to make the voltage unchanged, the current must be reduced, that is, the greater the resistance, the smaller the power.