A step up transformer increases 17.7v to 120v. what is the ratio of the current in the secondary compared to primary? Assume 92% efficiency.HELP PLEASE
Preliminary necessary comments. (i) This question - and consequently my answer - assumes that we have a perfect transformer: such a transformer will have an efficiency of 100 %. (If this was not a perfect transformer, then a great deal more data about the transformer would need to be supplied: it isn't). Hence, because the efficiency of the transformer in this question is less than 100%, that must be because a secondary current is flowing in the load, the details of which we do not know - or indeed need to know. (ii) Transformers are rated in terms of their product of volts and amps: called VA. They are NOT rated in terms of watts, since the manufacturer cannot assume that the load on the transformer secondary will have a unity power factor. (iii) When a transformer supplies current to a load, its on-load efficiency is the ratio of (VA)out to (VA)in. (VA)in primary VA; (VA)out secondary VA. Solution. Let the primary current Ip; let the secondary current Is. Let the primary voltage Vp; let the secondary voltage Vs. Let the efficiency n. Then we have: (VA)in Ip X Vp Ip X 17.7 (VA)out Is X Vs Is X 120. (VA)out n X (VA)in. so: Is X 120 0.92 X Ip X 17.7 i.e.: Is/Ip (0.92 X 17.7)/120 0.138/1 ? Hence, the secondary current is 0.138 that of the primary current. HTH, Skywave.
Any action picture that shows somebody getting thrown backwards with the aid of using a bullet hitting them is defying the regulation of physics which be sure with the contrary and equivalent reaction which states that the tension of a bullet flying could desire to additionally be transmitted to the shooter. in diverse words, it quite is impossible for the bullet hit to dramatically knock somebody over. indoors the somewhat international a bullet hit in basic terms is going into the physique, it does no longer throw it in any admire. there are various video clips that have the actors putting from wires to look as though they're flipping devoid of shock into the air at an identical time as appearing kicks and suchlike. that's feasible to end kicks and flips, regardless of if the action picture makes it look as though: a) it quite is undemanding b) takes awhile for the guy to land C) a sequence of kicks further with the aid of using somebody indoors the air are robbing the attacker of forward momentum. the belief of a guy or woman flying forwards and turning in many forward kicks in succession is neat to artwork out on exhibit exhibit, yet indoors the somewhat be wakeful those kicks could be ineffective if even extremely feasible. The matrix is a competent social gathering of those products, regardless of if it actually is argued that they weren't quite attempting to imitate somewhat international physics on the time. video clips like challenge Impossible2 3, Charlies Angels a million 2, and Mortal Kombat a million, 2 attempt the style of element a lot.
Sec Curren Ratiot 17.7/(120*0.92) 0.136
