Exercises of Ohm's law in Physics 1. Observe the name plate of the sliding rheostat. What are the words on it? What do they mean? 2. Observe the structure of the sliding rheostat. How many leads does it have? Which part of the sliding rheostat is connected to each lead? 3. Characteristics of resistance in series circuit?

1. The name plate of sliding rheostat is usually marked with a resistance value and a current value. For example, "50 Ω 2A" means that the maximum resistance of the sliding rheostat is 50 Ω, and the allowed large current is 2A
2. The sliding rheostat can have four lead out terminals, namely terminals. The two terminals above are connected with a metal rod, the two terminals below are connected with a section of resistance wire, and the slide plate connects the metal rod with the resistance wire. The effective connection method is one up and one down. The specific connection part depends on the terminal below
3. The characteristics of resistance in series circuit: the total resistance of series circuit is equal to the sum of series resistance, that is, r = R1 + R2

All the physical formulas about buoyancy should be derived! In a word, the more detailed the better, don't bother,

F floating = f (lower surface) - f (upper surface) = ρ GH2 * s - ρ GH1 * s = ρ GS * Δ H = ρ GV = g liquid discharge. When the object is suspended on the liquid (without external force), f floating = g object (where H2 is the distance from the lower surface of the cube to the water surface, H1 is the distance from the upper surface of the cube to the water surface, Δ h is the height of the cube)

Eighth grade volume II physical calculation formula

Physical formula (unit) formula remarks formula deformation series circuit current I (a) I = I1 = I2 = The current is equal everywhere, and the series circuit voltage U (V) u = U1 + U2 + The series circuit acts as a voltage divider, and the series circuit resistance R (Ω) r = R1 + R2 + Parallel circuit current I (a) I = I1 + I2 + Main road

Factorization: 25A ^ (n + 2) - 10A ^ (n + 1) + A ^ n

25a^(n+2)-10a^(n+1)+a^n
=25*a^2*a^n-10*a*a^n+a^n
=a^n(25a^2-10a+1)
=a^n(5a-1)

One seventh of () equals 1.1, and there are 12 ()

(7) One seventh equals 1.1, in which there are 12 (1 / 12)

It is known that the intersection of a straight line y = 2x + m and a circle x2 + y2 = 1 is at two different points a and B, and the angles with ox as the starting edge, OA and ob as the ending edges are α and β respectively, then the value of sin (α + β) is ()
A. 35B. −45C. −35D. 45

As shown in the figure, if O is used as OC ⊥ AB at point C, OC bisects ⊥ AOB, because the angles of ox as the starting edge, OA and ob as the ending edge are α and β respectively, so ⊥ AOD = α, ⊥ BOD = β, so ⊥ cod = α + β 2 is OC ⊥ AB, and the slope of AB is K1 = 2, so the slope of OC is K2 = - 12, so tan α + β 2 = - 12. According to the universal formula, sin (α + β) = 2 × (− 12) 1 + (− 12) 2 = - 45

150 + x = 2x (147-x) to solve the equation

We don't know whether the X after 2 is multiplied by or unknown, so we give two cases
150+x=2(147-x)
150+x=294-2x
3x=144
x=48
150+x=2x(147-x)
150+x=294x-2x^2
2x^2-293x+150=0

Let f (x) = - 2x ^ 2-2ax + A + 1 (x belongs to [- 1,0]), a > = 0 (1) find the minimum value of F (x), m (a) (2) find the minimum value of M (a), and point out the value of a at this time

(1) F (x) = - 2 (x + A / 2) &# 178; + A & # 178 / / 2 + A + 1, axis of symmetry x = - A / 2, opening downward
When a ≤ 0, - A / 2 ≥ 0, m (a) = f (- 1) = - 2 + 2A + A + 1 = 3a-1
②0

Fill in the numbers regularly: half, one third, two nineties, four 27th, (), ()

Eight out of eighty-one, sixteen out of 243
Multiply the previous number by two thirds

Let a = {X / X is greater than 1 and less than 2}, B = {X / AX-2 is less than 0}. If a is a proper subset of B, find the set composed of different values of real number a

When B = {x | ax0, B = {x | x = 2, the solution is 0