The output of my garden lighting transformer is 12 volts ac.
Is there any technical reason reason why ac is used as opposed to dc....or is it just the case of why not. I guess ac transformers are slightly cheaper than dc variants.
The bulbs are also marked as 12 Volts 7 watts. This would equate to a resistance of 20 ohms ?? (using the formula V squared divided by P)
When measured with a DVM the reading of the lamp is only 2 ohms.
I am surprised at such a large difference.
Can anyone explain how the bulb markings are calculated?
Is there any technical reason reason why ac is used as opposed to dc....or is it just the case of why not. I guess ac transformers are slightly cheaper than dc variants.
The bulbs are also marked as 12 Volts 7 watts. This would equate to a resistance of 20 ohms ?? (using the formula V squared divided by P)
When measured with a DVM the reading of the lamp is only 2 ohms.
I am surprised at such a large difference.
Can anyone explain how the bulb markings are calculated?