Two physics questions, the second year of junior high school, seek detailed solutions chasing suspe

1, Jia Liang, because: p amount = u amount * i amount, u amount = i amount * r, so: r = u amount * u amount p amount.

Then, calculate that the resistance of A is larger. B has a smaller resistance. After being connected in series, the current is the same, then, the power with a large resistance is large, because p real = u real * i real = i real * r * i real.

The power determines the brightness, so the actual power of A is larger, so the brightness of the A light is larger.

2.If the resistance is small, the rated power will be larger, because the rated voltage is the same, p = u * u r (here the above question 1 has been pushed out, no longer explained.) The larger the r, the smaller the p, and the smaller the r, the larger the p.

Because the resistance of the first lamp is large, the series current is the same, and the power of the first is known by w=i2 r, so it is a bright spot.

2。When the current is the same in series, the bulb with large resistance is bright, and the rated power of the bulb with large resistance is small if there is w=u2 r.

1. Calculate the resistance according to P=U2 R, the electric light with large resistance is on, because the current of the series circuit is the same, and the electrical power can be known to be proportional to the resistance according to P=I2R.

2. The resistance of the lamp is large, because the current of the series circuit is the same, and the rated power is calculated according to P=U2 R, it can be known that two small bulbs with the same rated voltage have a large resistance of the series lamp, so the rated power is small.

Root cause: Lack of familiarity with the basics.

20 tandem.

4 tandem 2 tandem AC

c220 36= round 7 lamps.

Kids, do you have time to get these words on the Internet, but don't you have time to do them yourself?

1::20 in series.

2: 4 Sections Tandem 3 Tandem 3: A

4: B is selected for series connection, and C is selected for parallel connection

5：c6: 220v/n=<36v => n>=220v/36v n=7

Question 1 (20) (string).

Question 2 (4) (string), (3) (string).

Question 3 (a).

Question 4 (c).

Question 5 (b).

Question 6 (6).

1. The family voltage is 220v, so it is 20 of the same small colored lights in series, and the voltage of the dry battery is 2, so it is 4 in series, and the battery voltage is 2v, so it is 3 in series and 3 in parallel, all of which are equal to the power supply voltage, so it is 1:1

4 choose C, the front is connected in series, and the back is in parallel.

5 parallel must be equal, if the resistance is equal when connected in series, the voltage is also equal, so choose C6 with 220 divided by 36.

pcs, in series.

knots, tandem, 3 knots, tandem.

3、a4、c

5, C 36 6 pcs.

20 in series.

4 dry cell strings, 3 battery strings, acc7

Item A refers to "the pressure of the two containers on the tabletop", that is, the gravity of the water and the container, and the landlord's method is to find the pressure of the water on the bottom of the container, which is equal, and the pressure on the table and the pressure on the container are different concepts.

For this question, choose d and b'It is conical, and after putting in the wooden block, the water rises more than A, so the landlord can find out that the pressure of water at the bottom of container B is greater than the pressure of water at the bottom of container A.

Formula: t=1 f So, t is between 1 120000 and 1 10000.

Slow Pitch Pitch is related to frequency (speed of vibration) Loudness Loudness is related to amplitude.

(1) 1 10000s (2) d (3) b (4) d (5) slow, ( different, this shows ( statement 1: the thickness of the material leads to the different pitch of the sound ; Claim 2: The thicker the rubber band, the lower the pitch), fast, and the amplitude of the pitch object is related to the small loudness.

Graph Column? I'll just guess what the picture looks like, but I guess right. 1) Horizontal distance s=vt=v h g= 2) pressure n-mg=f=mv 2 r so n=mg mv 2 r=3n 3) Can not,

Chinese physics problems are boring. Don't think about it at all, it's so damning.

Gigig7 acted as a ** trader.

The bulb is connected in parallel: A1 measures the total current, A2 measures the current of L2, S1 is connected in series with L1, and S2 is connected in series with L2.

S3 separates the bulb from the switch in the middle.

It's actually a bridge circuit, do you understand when I say that?

The top is a rectangle with a shape of two columns (no left and right, L1 on the top left, S1 on the bottom left, S2 on the bottom right, S3 in the middle) and a rectangle (A1 and Power) below. Two put together.

Oh, my God! I don't know how to draw.

L1 is placed where R1 is placed, S1 is placed where R2 is placed, L2A2 is placed where R3 is placed, S2 is placed where R4 is placed, and S3 is placed where G is placed

Place the power supply and A1

What kind of thing is this, I can't see it clearly, and I make a hair.

1dm 3= Let the volume of pure water be xm 3 then the volume of sediment is (the density of water is.

So xm 3*1 x 10 3 kg m3+

x is the volume of pure water and the mass of sediment contained in the water sample (

First, the water content is 1kg, and then the sediment mass is 0 03kg

So the sediment volume is 0 03 (2 5 10 ) 12 10 -6m =12 10 -3dm =1

Let the sediment volume t, water m, then 1x10 (-3)=m+t to find m and t, and then you can do that.

The volume of pure water is v cubic meters, then the volume of sand is.

The weight of the sand + the weight of the water, ie.

Solving this unary equation yields v= to the power -4.

Pulley 100N + Object 1300N = 1400NThe maximum bearing capacity of the rope is 300N, and the weight of the person is 400N, that is to say, the maximum pulling force of the person is 400N, and the person has to pull the rope.

Therefore, the maximum force blade used by a person on the rope is 300n300n x 5 = 1500n, just greater than 1400n, and the method of using 5 ropes to bear the weight. A child only needs to use a force of 1400 x 1 5 = 280N. Save 4 5 force 1400x4 5 = 1120n

The distance to be pulled should be 10m x 5 = 50m