A few questions about electric power in grade two of junior high school 1. How many hours can a bulb marked with 220 V and 100 W work for one degree of electricity? If the lamp is connected to a 110 V circuit, what is its actual power? 2. The bulb marked with 36V 40W is connected to a circuit, and the measured current is 1a. Then, what is the actual voltage and power of the bulb? 3. For the ammeter marked with 220 V 5a, how many 220 V 100 W bulbs can be connected at most? If these bulbs work for 5 hours a day, how many kwh can they use in 30 days? I can't do this kind of problem

A few questions about electric power in grade two of junior high school 1. How many hours can a bulb marked with 220 V and 100 W work for one degree of electricity? If the lamp is connected to a 110 V circuit, what is its actual power? 2. The bulb marked with 36V 40W is connected to a circuit, and the measured current is 1a. Then, what is the actual voltage and power of the bulb? 3. For the ammeter marked with 220 V 5a, how many 220 V 100 W bulbs can be connected at most? If these bulbs work for 5 hours a day, how many kwh can they use in 30 days? I can't do this kind of problem

1. 10 hours, 25w2, 32.432.4311 1651, t = w / P = 1kwh / 0.1kw = 10h, r = u sum & sup2 / P sum = (220V) & sup2 / 100W = 484 Ω, P real = u sum & sup2 / r = (110V) & sup2 / 484 Ω = 25w2, r = u sum & sup2 / P sum = (36V) & sup2 / 40W = 32.4 Ω, u real = I real, r = 1A * 32.4

1. Equipment: hard rod, object B (known density is Pb), object a, some liquid of unknown density, scale, thin line, beaker, measure liquid density
2. Equipment: large container, small plastic bucket, object a (density greater than water), enough water, scale, measure the density of A

Equipment: hard rod, object B (known density is Pb), object a, some liquid of unknown density, scale, thin line, beaker, measure liquid density
Let the density of the liquid to be measured be pa (PA should be less than Pb, otherwise there is no solution)
1. Fill a beaker with a proper amount of liquid a, and measure the liquid height as l0 with a scale; put object B into liquid a, and press B with a hard rod from above, so that B is completely immersed in a, and measure the liquid height as L1
The volume of object B is
VB=S（L1-L0）
2. Fill the beaker with liquid a and measure the height of liquid L2 with a scale; put object B into liquid a and immerse Part B into liquid a, then liquid overflows; take out B and measure the height of remaining liquid L3 in the beaker
The buoyancy of object B can be obtained as
PB*VB=PA*S（L2-L3）
PA = Pb * VB / S (L2-L3) = Pb * s (l1-l0) / S (L2-L3) = Pb * (l1-l0) / (L2-L3)
Equipment: large container, small plastic bucket, object a (density greater than water), enough water, scale, measure the density of A
These equipment can not measure the density of a, only the volume of A. the method is as shown in 1 of the same question

There are the following equipment on the experimental table: ejection dynamometer, scale, deep enough large water tank, square metal block with a side length of a and enough water, The pressure of water on the bottom of the metal block is proportional to the depth of the metal block immersed in water

You can follow the standard steps in the textbook
The idea is: measure the cube side length a, hook the metal block into the water tank, according to the depth B1 of the metal block and (gravity minus the reading of the dynamometer at the moment), record the data for many tests. It should be noted that the metal block can not be completely submerged. The formulas used are: F = KX, P = f / s, s = a ^ 2