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7. Use fundamental units to show the equation [tex]Q = 1 \times t[/tex] for electric charge passing a point in time [tex]t[/tex], when the electric current is 1, is homogeneous.

8. Use fundamental units to show that the equation [tex]P = I V[/tex] is homogeneous, where [tex]I[/tex] is electric current, [tex]V[/tex] is voltage, and [tex]P[/tex] is power measured in watts (W). (Hint: [tex]1 \, W = 1 \, \text{J} \, \text{s}^{-1}[/tex])


Sagot :

Sure, let's break this down step by step to show that both equations are homogeneous in terms of their respective units.

### Question 7

For the equation [tex]\( Q = 1 \times t \)[/tex], we need to prove that the units on both sides are consistent. Here, [tex]\( Q \)[/tex] is electric charge, and [tex]\( t \)[/tex] is time, with electric current given as 1.

1. Units of Electric Charge [tex]\( Q \)[/tex]:
- Electric charge [tex]\( Q \)[/tex] is measured in Coulombs (C).

2. Units of Electric Current [tex]\( I \)[/tex]:
- Electric current [tex]\( I \)[/tex] is measured in Amperes (A).
- Given [tex]\( I = 1 \)[/tex] A.

3. Units of Time [tex]\( t \)[/tex]:
- Time [tex]\( t \)[/tex] is measured in seconds (s).

From the basic relationship in electrical formulas:
[tex]\[ I = \frac{Q}{t} \][/tex]

Rearranging this to solve for [tex]\( Q \)[/tex]:
[tex]\[ Q = I \times t \][/tex]

Now, replacing the given values:
[tex]\[ Q = 1 \times t \][/tex]

Next, we confirm the homogeneity of the units:
- Electric charge [tex]\( Q \)[/tex] has units of Coulombs (C).
- Time [tex]\( t \)[/tex] has units of seconds (s).
- Since [tex]\( I \)[/tex] is electric current, it has units of Amperes (A).

Using the fundamental equation [tex]\( I = \frac{Q}{t} \)[/tex]:
[tex]\[ \text{1 Coulomb (C)} = \text{1 Ampere (A)} \times \text{1 second (s)} \][/tex]

This shows that:
[tex]\[ \text{C} = \text{A} \times \text{s} \][/tex]

Thus, the units on both sides of [tex]\( Q = 1 \times t \)[/tex] are homogeneous, as Coulombs are equivalent to [tex]\( \text{Ampere} \times \text{seconds} \)[/tex].

### Question 8

For the equation [tex]\( P = IV \)[/tex], we need to demonstrate that the units on both sides are consistent. Here, [tex]\( P \)[/tex] is power, [tex]\( I \)[/tex] is electric current, and [tex]\( V \)[/tex] is voltage.

1. Units of Power [tex]\( P \)[/tex]:
- Power [tex]\( P \)[/tex] is measured in Watts (W).

2. Units of Electric Current [tex]\( I \)[/tex]:
- Electric current [tex]\( I \)[/tex] is measured in Amperes (A).

3. Units of Voltage [tex]\( V \)[/tex]:
- Voltage [tex]\( V \)[/tex] is measured in Volts (V).

Given:
[tex]\[ P = I \times V \][/tex]

Next, we confirm the homogeneity of the units:
- Power [tex]\( P \)[/tex] has units of Watts (W).
- Electric current [tex]\( I \)[/tex] has units of Amperes (A).
- Voltage [tex]\( V \)[/tex] has units of Volts (V).

Using the known relationship:
[tex]\[ 1 \text{ Watt (W)} = 1 \text{ Ampere (A)} \times 1 \text{ Volt (V)} \][/tex]

Therefore:
[tex]\[ \text{W} = \text{A} \times \text{V} \][/tex]

This shows that the units on both sides of [tex]\( P = IV \)[/tex] are homogeneous, as Watts are equivalent to [tex]\( \text{Ampere} \times \text{Volts} \)[/tex].

In conclusion, we have shown that both equations [tex]\( Q = 1 \times t \)[/tex] and [tex]\( P = IV \)[/tex] are homogeneous with respect to their units.