Yes, 115V 60Hz will work in a 120V 60Hz power supply.
Yes, as long as the device is within 10% of the rated voltage.
You cannot use a 220v appliance to a 120v outlet.
120V appliance will not work on 220V. Use an instrument transformer or voltage regulator to adjust the high voltage to the desired level.
For residential service 110V, 115V, 117V, 120V, and 125V are all functionally the same. Electric companies have been slowly increasing the line voltage over the last 100 years to cope with increased loads. That is where these different voltages come from. The tolerance is generally +/-10%. That's +/- 11.5 volts in this case. So, a 115VAC appliance will run between 103.5 and 126.5VAC. The short answer is yes. 110V appliances can work with up to 130V without being burnt, additionally, 220V appliances can work with up to 240V without being burnt.
yes ofcourse they both are the same
No, the voltage is too high.
Yes, but you will only get one quarter of the wattage from the heater.
If I understand your question, Can you run a 110 appliance off of a 220 volt outlet? You could by only using one leg of the 220. You may also consider changing the outlet. Put in a regular 110 outlet and capping off one leg of the 220 in the wall box. You still have a neutral and a ground to work with. I read this as the questioner doesn't want to modify the outlet. Check the voltage ratings on the device. Many electronic devices nowadays can havdle 120V or 240V as it is cheaper to manufacture one powersupply and sell it everywhere. If your device is rated for 240V, you can put a 240V plug on it. If it only says 120V, no dice. 240V will burn it up.
1) Possible... You can buy a converter in any electrical supplies store. Plug in your appliance(s) in this converter then plug the converter into your 220V outlet. 2) Most of the Automatic Voltage Regulator has a 110V outlet. Plug in your appliance in this outlet and plug in the AVR in the 220V outlet. Hope I help you
Off hand no but your explanations are not clear as to who is doing what to whom,,