Chapter 20. Emf in an ac generator (20-7)

Question

vQTwIvkrY4rco6/QIcsmEWoqdA7zkCWZYopJ6Zg0dph0KxVg
{"title":"Emf produced by an ac generator","description":"Correct!","type":"correct","color":"#99CCFF","code":"[{\"shape\":\"poly\",\"coords\":\"82,133\"},{\"shape\":\"rect\",\"coords\":\"10,16,12,16\"},{\"shape\":\"poly\",\"coords\":\"144,22\"},{\"shape\":\"rect\",\"coords\":\"2,13,13,32\"}]"} {"title":"Angular speed of the rotating coil","description":"Wrong","type":"incorrect","color":"#ffcc00","code":"[{\"shape\":\"rect\",\"coords\":\"45,8,72,31\"},{\"shape\":\"rect\",\"coords\":\"201,13,225,29\"}]"} {"title":"Time","description":"Incorrect","type":"incorrect","color":"#333300","code":"[{\"shape\":\"rect\",\"coords\":\"223,7,237,30\"}]"} {"title":"Angle of the coil at t = 0","description":"Incorrect","type":"incorrect","color":"#000080","code":"[{\"shape\":\"rect\",\"coords\":\"267,5,291,36\"}]"} {"title":"Magnitude of the magnetic field to which the coil is exposed","description":"Incorrect","type":"incorrect","color":"#333333","code":"[{\"shape\":\"rect\",\"coords\":\"121,4,143,29\"}]"} {"title":"Area of the coil","description":"Incorrect","type":"incorrect","color":"#800000","code":"[{\"shape\":\"rect\",\"coords\":\"97,2,119,29\"}]"} {"title":"Number of turns in the coil","description":"Incorrect","type":"incorrect","color":"#FF6600","code":"[{\"shape\":\"rect\",\"coords\":\"74,3,95,29\"}]"}

Question

0Ls3g+nl0yfzuHQQMonaYHhULfbni8Nj1G25wIHZxxYrnteAQ0Ra2Q==
{"title":"Emf produced by an ac generator","description":"Incorrect","type":"incorrect","color":"#99CCFF","code":"[{\"shape\":\"poly\",\"coords\":\"82,133\"},{\"shape\":\"rect\",\"coords\":\"10,16,12,16\"},{\"shape\":\"poly\",\"coords\":\"144,22\"},{\"shape\":\"rect\",\"coords\":\"2,13,13,32\"}]"} {"title":"Angular speed of the rotating coil","description":"Correct!","type":"correct","color":"#ffcc00","code":"[{\"shape\":\"rect\",\"coords\":\"45,8,72,31\"},{\"shape\":\"rect\",\"coords\":\"201,13,225,29\"}]"} {"title":"Time","description":"Incorrect","type":"incorrect","color":"#333300","code":"[{\"shape\":\"rect\",\"coords\":\"223,7,237,30\"}]"} {"title":"Angle of the coil at t = 0","description":"Incorrect","type":"incorrect","color":"#000080","code":"[{\"shape\":\"rect\",\"coords\":\"267,5,291,36\"}]"} {"title":"Magnitude of the magnetic field to which the coil is exposed","description":"Incorrect","type":"incorrect","color":"#333333","code":"[{\"shape\":\"rect\",\"coords\":\"121,4,143,29\"}]"} {"title":"Area of the coil","description":"Incorrect","type":"incorrect","color":"#800000","code":"[{\"shape\":\"rect\",\"coords\":\"97,2,119,29\"}]"} {"title":"Number of turns in the coil","description":"Incorrect","type":"incorrect","color":"#FF6600","code":"[{\"shape\":\"rect\",\"coords\":\"74,3,95,29\"}]"}

Question

Rhin7ZJP9kY=
{"title":"Emf produced by an ac generator","description":"Wrong","type":"incorrect","color":"#99CCFF","code":"[{\"shape\":\"poly\",\"coords\":\"82,133\"},{\"shape\":\"rect\",\"coords\":\"10,16,12,16\"},{\"shape\":\"poly\",\"coords\":\"144,22\"},{\"shape\":\"rect\",\"coords\":\"2,13,13,32\"}]"} {"title":"Angular speed of the rotating coil","description":"Wrong","type":"incorrect","color":"#ffcc00","code":"[{\"shape\":\"rect\",\"coords\":\"45,8,72,31\"},{\"shape\":\"rect\",\"coords\":\"201,13,225,29\"}]"} {"title":"Time","description":"Correct!","type":"correct","color":"#333300","code":"[{\"shape\":\"rect\",\"coords\":\"223,7,237,30\"}]"} {"title":"Angle of the coil at t = 0","description":"Incorrect","type":"incorrect","color":"#000080","code":"[{\"shape\":\"rect\",\"coords\":\"267,5,291,36\"}]"} {"title":"Magnitude of the magnetic field to which the coil is exposed","description":"Incorrect","type":"incorrect","color":"#333333","code":"[{\"shape\":\"rect\",\"coords\":\"121,4,143,29\"}]"} {"title":"Area of the coil","description":"Incorrect","type":"incorrect","color":"#800000","code":"[{\"shape\":\"rect\",\"coords\":\"97,2,119,29\"}]"} {"title":"Number of turns in the coil","description":"Incorrect","type":"incorrect","color":"#FF6600","code":"[{\"shape\":\"rect\",\"coords\":\"74,3,95,29\"}]"}

Question

tjzs0eyn54yVEOSqjOmI+x4OAZEL4Up9c0Yabd3ANtO3BIqg
{"title":"Emf produced by an ac generator","description":"Wrong","type":"incorrect","color":"#99CCFF","code":"[{\"shape\":\"poly\",\"coords\":\"82,133\"},{\"shape\":\"rect\",\"coords\":\"10,16,12,16\"},{\"shape\":\"poly\",\"coords\":\"144,22\"},{\"shape\":\"rect\",\"coords\":\"2,13,13,32\"}]"} {"title":"Angular speed of the rotating coil","description":"Wrong","type":"incorrect","color":"#ffcc00","code":"[{\"shape\":\"rect\",\"coords\":\"45,8,72,31\"},{\"shape\":\"rect\",\"coords\":\"201,13,225,29\"}]"} {"title":"Time","description":"Incorrect","type":"incorrect","color":"#333300","code":"[{\"shape\":\"rect\",\"coords\":\"223,7,237,30\"}]"} {"title":"Angle of the coil at t = 0","description":"Correct!","type":"correct","color":"#000080","code":"[{\"shape\":\"rect\",\"coords\":\"267,5,291,36\"}]"} {"title":"Magnitude of the magnetic field to which the coil is exposed","description":"Incorrect","type":"incorrect","color":"#333333","code":"[{\"shape\":\"rect\",\"coords\":\"121,4,143,29\"}]"} {"title":"Area of the coil","description":"Incorrect","type":"incorrect","color":"#800000","code":"[{\"shape\":\"rect\",\"coords\":\"97,2,119,29\"}]"} {"title":"Number of turns in the coil","description":"Incorrect","type":"incorrect","color":"#FF6600","code":"[{\"shape\":\"rect\",\"coords\":\"74,3,95,29\"}]"}

Question

6iYhkbCU8atwaWpLMHCrPeQjJqiQlDadVszb9x/1nSptv36BVrVJ8YvxQK53d8fZTzf3O+UGM6gbv1GbkVspbw==
{"title":"Emf produced by an ac generator","description":"Wrong","type":"incorrect","color":"#99CCFF","code":"[{\"shape\":\"poly\",\"coords\":\"82,133\"},{\"shape\":\"rect\",\"coords\":\"10,16,12,16\"},{\"shape\":\"poly\",\"coords\":\"144,22\"},{\"shape\":\"rect\",\"coords\":\"2,13,13,32\"}]"} {"title":"Angular speed of the rotating coil","description":"Wrong","type":"incorrect","color":"#ffcc00","code":"[{\"shape\":\"rect\",\"coords\":\"45,8,72,31\"},{\"shape\":\"rect\",\"coords\":\"201,13,225,29\"}]"} {"title":"Time","description":"Incorrect","type":"incorrect","color":"#333300","code":"[{\"shape\":\"rect\",\"coords\":\"223,7,237,30\"}]"} {"title":"Angle of the coil at t = 0","description":"Incorrect","type":"incorrect","color":"#000080","code":"[{\"shape\":\"rect\",\"coords\":\"267,5,291,36\"}]"} {"title":"Magnitude of the magnetic field to which the coil is exposed","description":"Correct!","type":"correct","color":"#333333","code":"[{\"shape\":\"rect\",\"coords\":\"121,4,143,29\"}]"} {"title":"Area of the coil","description":"Incorrect","type":"incorrect","color":"#800000","code":"[{\"shape\":\"rect\",\"coords\":\"97,2,119,29\"}]"} {"title":"Number of turns in the coil","description":"Incorrect","type":"incorrect","color":"#FF6600","code":"[{\"shape\":\"rect\",\"coords\":\"74,3,95,29\"}]"}

Question

wS+Jhr66RBG339xGjDbbhMx/EFg=
{"title":"Emf produced by an ac generator","description":"Wrong","type":"incorrect","color":"#99CCFF","code":"[{\"shape\":\"poly\",\"coords\":\"82,133\"},{\"shape\":\"rect\",\"coords\":\"10,16,12,16\"},{\"shape\":\"poly\",\"coords\":\"144,22\"},{\"shape\":\"rect\",\"coords\":\"2,13,13,32\"}]"} {"title":"Angular speed of the rotating coil","description":"Wrong","type":"incorrect","color":"#ffcc00","code":"[{\"shape\":\"rect\",\"coords\":\"45,8,72,31\"},{\"shape\":\"rect\",\"coords\":\"201,13,225,29\"}]"} {"title":"Time","description":"Incorrect","type":"incorrect","color":"#333300","code":"[{\"shape\":\"rect\",\"coords\":\"223,7,237,30\"}]"} {"title":"Angle of the coil at t = 0","description":"Incorrect","type":"incorrect","color":"#000080","code":"[{\"shape\":\"rect\",\"coords\":\"267,5,291,36\"}]"} {"title":"Magnitude of the magnetic field to which the coil is exposed","description":"Incorrect","type":"incorrect","color":"#333333","code":"[{\"shape\":\"rect\",\"coords\":\"121,4,143,29\"}]"} {"title":"Area of the coil","description":"Correct!","type":"correct","color":"#800000","code":"[{\"shape\":\"rect\",\"coords\":\"97,2,119,29\"}]"} {"title":"Number of turns in the coil","description":"Incorrect","type":"incorrect","color":"#FF6600","code":"[{\"shape\":\"rect\",\"coords\":\"74,3,95,29\"}]"}

Question

bAb6QL/E4/bCaXaavpSR/F8fGHdc+GhnzdjePT6aYms=
{"title":"Emf produced by an ac generator","description":"Wrong","type":"incorrect","color":"#99CCFF","code":"[{\"shape\":\"poly\",\"coords\":\"82,133\"},{\"shape\":\"rect\",\"coords\":\"10,16,12,16\"},{\"shape\":\"poly\",\"coords\":\"144,22\"},{\"shape\":\"rect\",\"coords\":\"2,13,13,32\"}]"} {"title":"Angular speed of the rotating coil","description":"Wrong","type":"incorrect","color":"#ffcc00","code":"[{\"shape\":\"rect\",\"coords\":\"45,8,72,31\"},{\"shape\":\"rect\",\"coords\":\"201,13,225,29\"}]"} {"title":"Time","description":"Incorrect","type":"incorrect","color":"#333300","code":"[{\"shape\":\"rect\",\"coords\":\"223,7,237,30\"}]"} {"title":"Angle of the coil at t = 0","description":"Incorrect","type":"incorrect","color":"#000080","code":"[{\"shape\":\"rect\",\"coords\":\"267,5,291,36\"}]"} {"title":"Magnitude of the magnetic field to which the coil is exposed","description":"Incorrect","type":"incorrect","color":"#333333","code":"[{\"shape\":\"rect\",\"coords\":\"121,4,143,29\"}]"} {"title":"Area of the coil","description":"Wrong","type":"incorrect","color":"#800000","code":"[{\"shape\":\"rect\",\"coords\":\"97,2,119,29\"}]"} {"title":"Number of turns in the coil","description":"Correct!","type":"correct","color":"#FF6600","code":"[{\"shape\":\"rect\",\"coords\":\"74,3,95,29\"}]"}

Review

The emf alternates with angular frequency \(\omega\), the same as the angular speed of the rotating coil. The maximum value of the emf is \(\epsilon_{\mathrm{max}} = \omega NAB\), which shows that we can increase the maximum emf by increasing the angular speed \(\omega\), the number of turns \(N\), the coil area \(A\), the magnetic field magnitude \(B\), or a combination of these.