The ram of a hydraulic press developed a force of 780 N when a pressure of 150 N is exerted on the plunger with a diameter of 90 mm. Calculate the diameter of the ram in (mm). Calculate the fluid pressure.

The diameter of the plunger ($d_P$) is $90 \text{ mm}$, which is $0.09 \text{ m}$.
The area of the plunger ($A_P$) is given by the formula $A = \frac{\pi d^2}{4}$.

The force on the plunger ($F_P$) is $150 \text{ N}$.
The fluid pressure ($P$) is given by $P = \frac{F_P}{A_P}$.

The force developed by the ram ($F_R$) is $780 \text{ N}$. According to Pascal's principle, the pressure is uniform throughout the fluid, so the pressure on the ram is also $P$.
The area of the ram ($A_R$) is given by $A_R = \frac{F_R}{P}$.

The diameter of the ram ($d_R$) is given by $d_R = \sqrt{\frac{4 A_R}{\pi}}$.

Converting to millimeters:

The diameter of the ram is $\boxed{\text{205.38 mm}}$.

1.1.2 Calculate the fluid pressure.

The fluid pressure was calculated in Step 2 of 1.1.1.

The fluid pressure is $\boxed{\text{23578.9 Pa}}$.

1.2 Calculate the number of teeth of gear Y.

For gears W and X: $\frac{N_X}{N_W} = \frac{T_W}{T_X}$
For gears Y and Z: $\frac{N_Z}{N_Y} = \frac{T_Y}{T_Z}$

Gears X and Y are on the same shaft, so their rotational speeds are equal: $N_X = N_Y$.

We know $N_W = 1800 \text{ r/min}$ (input speed) and $N_Z = 25 \text{ r/min}$ (output speed).
From the gear ratio equations:
$N_X = N_W \frac{T_W}{T_X}$
$N_Y = N_Z \frac{T_Z}{T_Y}$
Since $N_X = N_Y$:

Rearrange to solve for $T_Y$:

$N_W = 1800 \text{ r/min}$
$N_Z = 25 \text{ r/min}$
$T_W = 20$ teeth
$T_X = 120$ teeth
$T_Z = 160$ teeth

Since the number of teeth must be a whole number, there might be a slight rounding in the problem's given speeds or teeth counts, or it implies a non-integer ratio. However, in practical gear design, teeth are integers. If we assume the values are exact, the result is not an integer. Let's recheck the calculation.
$25 \times 160 \times 120 = 480000$
$1800 \times 20 = 36000$
$480000 / 36000 = 480 / 36 = 40 / 3 = 13.333...$

It's possible the problem expects a rounded answer or there's an error in the problem statement's numbers. Given that teeth must be integers, I will provide the exact fraction and note the non-integer result. However, if this is a multiple choice question, I would look for the closest integer. Assuming it expects an exact calculation:

The number of teeth of gear Y is $\boxed{\text{13.33}}$.

1.3 Name the measuring equipment used to measure each of the following in electrical circuits:

1.3.1 Potential difference
A voltmeter is used to measure potential difference.

1.3.2 Resistance
An ohmmeter is used to measure resistance.