Chip resistor package 0805 can replace 0603 package, the same resistance?

No problem. The resistance of 0805 package is higher than that of 0603 package. As long as the resistance is the same, it can be replaced

What is the resistance of chip resistor 0603 (47a) and chip resistor 0805 (6r19)

The label of the chip resistor is related to the manufacturer and does not directly indicate the specific resistance value. Therefore, to see this label, you need to read the corresponding product manual to know what is going on
The most convenient way is to directly measure. Or look at the schematic diagram. You can't see the logo. Unless you know which manufacturer it is. You can check the manual again. The chance is slim. Ha

The crystal oscillator circuit is as follows. What is the function of a 100 ohm resistor connected in series?

The function of resistance and capacitance at both ends of crystal oscillator circuit:
The four functions of parallel resistance are as follows
1. The amplifier works in the linear region with negative feedback and phase shift;
2. Current limiting prevents the resonator from being overdriven;
3. The parallel connection reduces the resonance impedance and makes the resonator easy to start;
4. The value of resistance affects the pulse width of waveform
Function of capacitance at both ends:
This is the matching capacitance of the crystal. Only when the external capacitance is the matching capacitance, can the oscillation frequency be within the error range near the nominal frequency. It is best to use the data provided, if not, it is generally about 30pf. It is too small to start oscillation. In some cases, the oscillation frequency can be adjusted by adjusting the size of the two capacitors, Of course, the adjustable range is generally in the order of 10ppm
Usually accumulated, you see if you can help you solve this problem

The crystal oscillator circuit is as follows. What is the function of a 10m ohm resistor in parallel?

Provides closed loop damping

A 5 ohm resistor and a 20 ohm resistor are connected in series. The equivalent resistance is 25 Ohm. If they are connected in parallel, what is the equivalent resistance

The reciprocal of the parallel resistance is equal to the sum of the reciprocal of the single resistance, so 20 × 5 / (20 + 5) = 4 ohm

There is a bulb marked pz220v40w, which is connected to the 220 V home circuit (with the bulb resistance unchanged). (1) calculate the resistance of the bulb when it normally emits light. (2) if the actual voltage is 200 V, what is the actual power of the bulb? What is the light emission condition of the bulb?

(1) From P = u ^ 2 / R, r = u ^ 2 / P = 220 ^ 2 / 40 = 1210 Ω
(2) And P = u ^ 2 / r = 200 ^ 2 / 1210 = 33W. The actual power of the bulb becomes smaller and the brightness of the light becomes smaller

What is the total power of 700W and 900W consumers in series and in parallel
The rated voltage is 220 v

1600W in parallel
series connection
700W resistance 69 Ω 900W resistance 54 Ω
Total resistance 123 ohm
Current 1.8A
Total power 1.8A squared by 69 Ω + 1.8A squared by 54 Ω = 399w
Rounding is used in the calculation, there are some errors, but the process and idea are absolutely right

Power in series and parallel
For resistance
Concatenation is the sum of them
Parallel connection (2) is equal to their product divided by their sum
that
For power
Do you have a similar formula

For power
The total power is equal to the sum of the partial power
Whether in series or in combination

If the voltage increases to 2 times of the original, the power of the electric appliance will be several times of the original
When a consumer is connected to the circuit, if the voltage increases to 2 times of the original, the power of the consumer will be several times of the original; if the power on time increases to 2 times of the original, the power will be several times of the original; if the resistance of the consumer is increased to 2 times of the original, and the electric power remains unchanged, the voltage at both ends of the consumer will be several times of the original

1,4 times. 2, unchanged. 3, root 2 times

Rated power of three-phase motor = rated voltage * root 3 * rated current * power factor
Why take root 3,

The line voltage (380V) is expanded by 3 (1.732) times of the root, which is equal to 3 times of the phase voltage (220V) (660V). Thus, the calculation result is the sum of three powers per phase
Namely:
Rated power of three-phase motor = rated voltage × root 3 × rated current × power factor = rated (phase) voltage × rated current × power factor × 3

Chip resistor package 0805 can replace 0603 package, the same resistance?