{"id":2066,"date":"2020-10-20T15:06:05","date_gmt":"2020-10-20T10:06:05","guid":{"rendered":"https:\/\/murreeroad.org\/physics10\/?p=2066"},"modified":"2020-10-20T19:47:11","modified_gmt":"2020-10-20T14:47:11","slug":"physics-10th-chapter-15-numerical-problems","status":"publish","type":"post","link":"https:\/\/murreeroad.org\/physics10\/physics-10th-chapter-15-numerical-problems\/","title":{"rendered":"Physics 10th chapter 15 Numerical Problems"},"content":{"rendered":"

<\/a>Chapter 15 Electromagnetism (Numerical Problems)<\/strong><\/span><\/p>\n

15.1. A transformer is needed to convert a mains 240 V supply into a 12 V supply. If there are 2000 turns on the primary coil, then find the number of turns on the secondary coil.\u00a0\u00a0<\/a><\/strong>
\n15.2. A step-up transformer has a turn ratios of 1 : 100. An alternating supply of 20 V is connected across the primary coil. What is the secondary voltage?\u00a0<\/a><\/strong>
\n15.3. A step-down transformer has a turns ratio of 100 : 1. An ac voltage of amplitude 170 V is applied to the primary. If the current in the primary is 1.0 mA, what is the current in the secondary?\u00a0\u00a0<\/a><\/strong>
\n15.4. A transformer, designed to convert the voltage from 240 V A.C mains to 12 V, has 4000 turns on the primary coil. How many turns should be on the secondary coil? If the transformer were 100% efficient, what current would flow through the primary coil when the current in the secondary coil was 0.4 A?<\/a><\/strong>
\n15.5. A power station generates 500 MW of electrical power which is fed to a transmission line. What current would flow in the transmission line, if the input voltage is 250 kV?<\/a><\/a><\/strong><\/p>\n

15.1. A transformer is needed to convert a mains 240 V supply into a 12 V supply. If there are 2000 turns on the primary coil, then find the number of turns on the secondary coil.\u00a0\u00a0<\/strong><\/p>\n

Solution: Given data<\/strong><\/p>\n

Voltage across primary Vp<\/sub> = 240 Volts<\/p>\n

Voltage across secondary Vs<\/sub> = 12 volts<\/p>\n

Number of turns of primary coil Np<\/sub> = 200<\/p>\n

Number of turns of secondary coil Ns = ?<\/p>\n

Formula Ns<\/sub> \/ Np<\/sub> = Vs<\/sub> \/ Vp<\/sub><\/p>\n

putting values we get Ns = (Vs<\/sub> \/ Vp<\/sub> ) x Np<\/sub><\/p>\n

Ns<\/sub> = (12\/240) x 200<\/p>\n

Ns<\/sub> = 100<\/p>\n

So, there are 100 turns in the secondary coil.<\/a>
\n15.2. A step-up transformer has a turn ratios of 1 : 100. An alternating supply of 20 V is connected across the primary coil. What is the secondary voltage?\u00a0<\/strong><\/p>\n

Solution: Given data<\/strong><\/p>\n

We have step up transformer<\/p>\n

Turn ratio is 1:100 It mean Np<\/sub>:Ns<\/sub> = 1:100<\/p>\n

\u21d2\u00a0 \u00a0Np<\/sub> \/ Ns<\/sub> = 1\/100<\/p>\n

Voltage across primary Vp<\/sub> = 20 Volts<\/p>\n

Voltage across secondary Vs<\/sub> = ?<\/p>\n

Formula: Vs \/ Vp<\/sub> = Ns<\/sub>\/Np<\/sub><\/p>\n

Putting the values we get<\/p>\n

Vs<\/sub> = 100 x 20<\/p>\n

Vs<\/sub> = 2000 Volts<\/p>\n

Hence 2000 volts will be produced across the secondary coil.<\/a><\/p>\n

15.3. A step-down transformer has a turns ratio of 100 : 1. An ac voltage of amplitude 170 V is applied to the primary. If the current in the primary is 1.0 mA, what is the current in the secondary?\u00a0\u00a0<\/strong><\/p>\n

Solution: Given data<\/strong><\/p>\n

We have step down transformer<\/p>\n

Turn ratio is 1:100 It mean Ns<\/sub> : Np<\/sub> = 1 : 100<\/p>\n

Ns<\/sub> \/ Np<\/sub> = 1\/100<\/p>\n

Voltage across primary Vp<\/sub> = 170 Volts<\/p>\n

Current across primary Ip<\/sub> = 1.0 mA = 1.0 x 10-3<\/sup> ampere<\/p>\n

Current across secondary Is<\/sub> = ?<\/p>\n

Formula: Vs \/ Vp<\/sub> = Ns<\/sub>\/Np<\/sub><\/p>\n

Putting the values we get<\/p>\n

Vs<\/sub> \/ Vp<\/sub> = 1 \/100<\/p>\n

We know that P = IV and by law of conservation of energy.<\/p>\n

Output Power = Input Power<\/p>\n

Is<\/sub> Vs<\/sub> = Ip<\/sub>Vp<\/sub><\/p>\n

Is<\/sub> = Ip<\/sub> x Vp<\/sub> \/ Vs<\/sub><\/p>\n

Is = 1.0 x 10-3<\/sup> x 100<\/p>\n

Is<\/sub> = 0.1 Ampere<\/p>\n

Hence 0.1 Ampere current will flow in the secondary coil.<\/a><\/p>\n

15.4. A transformer, designed to convert the voltage from 240 V a.c mains to 12 V, has 4000 turns on the primary coil. How many turns should be on the secondary coil? If the transformer were 100% efficient, what current would flow through the primary coil when the current in the secondary coil was 0.4 A?<\/strong><\/p>\n

Solution: Given data<\/strong><\/p>\n

We have step down transformer<\/p>\n

Voltage across primary Vp<\/sub> = 240 Volts<\/p>\n

Voltage across secondary Vs<\/sub> = 12 Volts<\/p>\n

Number of turns of primary coil Np<\/sub> = 4000<\/p>\n

Number of turns of secondary coil Ns<\/sub> = ?<\/p>\n

The transformer is 100 % it means Output power = Input power<\/p>\n

Is<\/sub>Vs<\/sub> = Ip<\/sub>Vp<\/sub><\/p>\n

Current across secondary coil Is = 0.4 Ampere<\/p>\n

Current across primary Ip<\/sub> = ?<\/p>\n

Formula: Ns<\/sub> \/ Np<\/sub> = Vs<\/sub> \/ Vp<\/sub><\/p>\n

Ns<\/sub> = (12\/240) x 400<\/p>\n

Ns<\/sub> = 200<\/p>\n

We know P = IV and by law of conservation of energy<\/p>\n

Input power = Output power<\/p>\n

Ip<\/sub>Vp<\/sub> = Is<\/sub>Vs<\/sub><\/p>\n

Therefore Ip<\/sub> = Is<\/sub> x Vs<\/sub> \/ Vp<\/sub><\/p>\n

putting value we get<\/p>\n

Ip<\/sub> = 0.4 x (12\/240)<\/p>\n

Ip<\/sub> = 0.02 Ampere<\/p>\n

Hence, 0.02 Ampere current will flow in the primary coil.<\/a><\/p>\n

15.5. A power station generates 500 MW of electrical power which is fed to a transmission line. What current would flow in the transmission line, if the input voltage is 250 kV?<\/strong><\/p>\n

Solution: Given data<\/strong><\/p>\n

Power generated P = 500MW = 500 x 106<\/sup> watt<\/p>\n

\u2234 1M = 106<\/sup><\/p>\n

Input voltage Vin<\/sub> = 250 kV = 250 x 103<\/sup> volts<\/p>\n

Current I = ?<\/p>\n

We know power P = IV<\/p>\n

We can write Pin<\/sub> = Iin<\/sub> Vin<\/sub><\/p>\n

Iin<\/sub> = Pin<\/sub> \/ Vin<\/sub><\/p>\n

Putting the values we get<\/p>\n

Iin<\/sub> = (500 x 106<\/sup> ) \/ (250 x 103<\/sup> )<\/p>\n

Iin<\/sub> = 2.0 x 103<\/sup> A<\/p>\n

 <\/p>\n

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 <\/p>\n

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Chapter 15 Electromagnetism (Numerical Problems) 15.1. A transformer is needed to convert a mains 240 V supply into a 12 V supply. If there are 2000 turns on the primary coil, then find the number of turns on the secondary coil.\u00a0\u00a0 15.2. A step-up transformer has a turn ratios of 1 : 100. An alternating… Read More »Physics 10th chapter 15 Numerical Problems<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"neve_meta_sidebar":"","neve_meta_container":"","neve_meta_enable_content_width":"off","neve_meta_content_width":0,"neve_meta_title_alignment":"","neve_meta_author_avatar":"","neve_post_elements_order":"","neve_meta_disable_header":"","neve_meta_disable_footer":"","neve_meta_disable_title":""},"categories":[9],"tags":[],"_links":{"self":[{"href":"https:\/\/murreeroad.org\/physics10\/wp-json\/wp\/v2\/posts\/2066"}],"collection":[{"href":"https:\/\/murreeroad.org\/physics10\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/murreeroad.org\/physics10\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/murreeroad.org\/physics10\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/murreeroad.org\/physics10\/wp-json\/wp\/v2\/comments?post=2066"}],"version-history":[{"count":8,"href":"https:\/\/murreeroad.org\/physics10\/wp-json\/wp\/v2\/posts\/2066\/revisions"}],"predecessor-version":[{"id":2075,"href":"https:\/\/murreeroad.org\/physics10\/wp-json\/wp\/v2\/posts\/2066\/revisions\/2075"}],"wp:attachment":[{"href":"https:\/\/murreeroad.org\/physics10\/wp-json\/wp\/v2\/media?parent=2066"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/murreeroad.org\/physics10\/wp-json\/wp\/v2\/categories?post=2066"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/murreeroad.org\/physics10\/wp-json\/wp\/v2\/tags?post=2066"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}