Joule s law, physics masters, please enter, please answer in detail

q=w=pt=u²/r×t∵t1：t2=1:2,r1:

r2=2:1, so 1min in parallel, q1=1 10q total, q2=1 20q total, t=q total (q1+q2)=1 (3 20)=20 3min

When connected in series, Q total = U1 R1T + U2 R2T, U1: U2 = 1:2, T = Q total (U1 R1 + U2 R2) because the voltage of R1 is the original 1 3, so U1 = 1 9, U2 is the original 2 3, so U2 square = 4 9.

So t=q total (1 9q1+4 9q2)=q total (1 90+2 90)=30min

I hope the landlord is satisfied, and if you have any questions, you can ask.

The heat q voltage u is the same.

q=(u²/r1)×t1...

q=(u²/r2)×t2---r1/r2=1/2 r2=2r1 ..

q=u (r1+r2) t3 ..

Substitution by U=QR1 T1 to T3=[(R1+R2) R1] T1=3T1=30min

w=u^2/r*t

w=u^2/r1*t1=u^2/r2*t22r1=r2

In series: r string = r1 + r2 = 3r1

w=u 2 r string*t string=u 2 (3r1)*t string=u 2 r1*t1 So t string=3t1=30min

In parallel: r and = (r1*r2) (r1 + r2) = 2r1 3w=u 2 r and * t and = t and * (3*u 2) (2r1) = u 2 r1*t1 so t and = 2t1 3=20 3 min

Let the first stage of resistance be r, and it will take 10min

The second stage of resistance is 2R, which takes 20min

When connected in series, the total resistance is 3R, and it takes 30min

When connected in parallel, the total electrical group is 2r 3, and the time is 20 3min

Joule's law is a law that quantitatively states that conductive current converts electrical energy into thermal energy. In 1841, Nachizakura, the British physicist Joule, discovered that the heat q (called Joule heat) generated in a current-carrying conductor is proportional to the square of the current i, the resistance r of the conductor, and the energizing time t, which is called Joule's law.

Joule's law stipulates that the heat generated by the electric cong flow through the conductor is proportional to the resistance of the conductor, proportional to the square of the current passing through the conductor, and proportional to the time of energizing. This law was discovered by the British scientist Joule in 1841.

Joule's law is an experimental law that can be applied to any conductor in a wide range and can be used in all circuits.

When encountering the thermal effect of electric current, such as calculating the heat emitted when an electric current passes through a circuit; Joule's law can be used when comparing how much heat is emitted by a certain section of a circuit or conductor, i.e., when considering the requirements for a circuit from the perspective of the thermal effect of the current.

When an electric current passes through a conductor, heat will be generated, which is called the thermal effect of electric current, and an electric heater is a device that uses the thermal effect of electric current to heat, electric stoves, electric soldering irons, electric irons, electric rice cookers, electric ovens, etc. are all common electric heaters. The main component of the electric heater is the heating element, which is made of resistance wire with high resistivity and high melting point wound on the insulating material.

Joules are basically non-lethal. Picking up a mobile phone from the ground does the work of having a dojoule.

To achieve the effect of "killing", among the existing **, the initial kinetic energy of the hand round simple gun is generally about 300J, the assault rifle is 1000-2000, the submachine gun is about 600, the anti-personnel sniper rifle is generally 3500, and the anti-equipment sniper rifle is generally more than 10,000.

The discovery of Joule's law.

It is expressed by the following formula: q=i 2*rt(j).

i = current through the conductor, a;

r=effective resistance of the conductor, ;

t = power-on time, s.

Jiao" was founded in honor of the famous physicist James Prescott Joule.

Although it is correct to denote joules as Newton meters in terms of units, this usage is generally discouraged in order to avoid confusion with the unit of moment. The physical meaning of moment is quite different from energy.

For purely resistive circuits, Ohm's law u=ir is constant, so the electrical power is not only equal to i r, but also to u r.

When there is only one resistor in the circuit, the resistance value increases, and the voltage u at both ends of the circuit does not change, so the u r becomes smaller, so the electrical power becomes smaller.

You can do extreme thinking. When the resistance is infinite, it is an open circuit, and the electrical power should obviously be 0. When the resistance is infinitesimal, it is a short circuit and the circuit will burn out. Why does it burn out? Because the power is too much.

In addition, for non-resistive circuits, such as electric motors in the circuit, then Ohm's law does not hold true for the entire circuit. Let the power supply voltage be U, the circuit current is I, the power of the motor is P, and the internal resistance is R, then the formula of the circuit is UI=P+I R. This can also explain why it is dangerous to turn on the power supply of the electric fan, and block the blades from turning it.

Because at this time, the mechanical power of the electric fan, that is, the electric power of the motor p=0, so according to the above formula ui=i r, that is, the electric power of the power supply is all used to heat the internal resistance of the electric fan, so the electric fan is likely to be burned out.

Can you send it in, or I won't be able to solve it for you, but I can tell you in no uncertain terms that your problem should be solved using the relationship between voltage and resistance (p is proportional to you and inversely proportional to r) instead of current and resistance.

The meaning of the formula is to choose one as the object of comparison when the other quantities remain the same.

The premise for this to be true is the control variable. It's like the first floor said.

The heat of the current is generated.

Effect - Mention Joule's law

At the age of 24, Jiao.

1. Joule's law is a law that quantitatively explains that conduction current converts electrical energy into thermal energy.

2. The content is: the fiber heat generated by the current through the conductor is proportional to the quadratic of the current, proportional to the resistance of the conductor, and proportional to the time of energizing. Joule's Law Mathematical Expression:

q=i2rt；For a pure resistive circuit, it can be deduced: q=w=pt; q=uit;q=(u2/r)t。