{"id":29720,"date":"2026-03-10T09:55:41","date_gmt":"2026-03-10T09:55:41","guid":{"rendered":"https:\/\/srmtradingcorporation.com\/?post_type=product&#038;p=29720"},"modified":"2026-03-10T09:55:58","modified_gmt":"2026-03-10T09:55:58","slug":"post-office-box-po-box-for-physics-practical","status":"publish","type":"product","link":"https:\/\/srmtradingcorporation.com\/?product=post-office-box-po-box-for-physics-practical","title":{"rendered":"Post Office Box (PO Box) for Physics Practical"},"content":{"rendered":"<p>A post office box is a compact form of the Wheatstone\u2019s bridge. A Post Office Box can also be used to measure an unknown resistance. It is a Wheatstone Bridge with three arms P, Q, and R; while the fourth arm is the unknown resistance. P and Q are known as the ratio arms while R is known as the rheostat arm.<\/p>\n<h2>Post Office Box (PO Box) for Physics Practical Class &amp; Exam<\/h2>\n<p>Plug-in type. The heavy brass contact blocks are bonded to the vulcanite plated by a double nut system. The plugs &amp; lugs are cut to a finer taper &amp; are interchangeable. The plug heads are machine molded of bakelite.<\/p>\n<p>Each resistor is independently mounted with double leads. The accuracy of Constantan coils is 0.1% for lower values &amp; 0.5% for higher values. Resistor: the best-imported constant wire is wound on ebonite spools; the method adopted is non-inductive &amp; non-magnetic. Each resistor is dipped in boiling wax. Provided as above with 3 ratio coils of 1000, 100 &amp; 10 ohms. Rheostat arm 15,000 ohms. Two tapping keys with silver contacts are provided for the battery &amp; galvanometer in a teakwood case with a hinged lid.<\/p>\n<ul>\n<li>Overall dimensions: 280x200x175mm approx.<\/li>\n<li>Premium Quality PO\u00a0Box<\/li>\n<li>Made in Bangladesh<\/li>\n<li>Note: Product Color, Size &amp; Size may be different from the picture.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<ul>\n<li>Deshi Post Office Box 1 Set<\/li>\n<li>Measure an unknown resistance<\/li>\n<li>Premium Quality PO Box<\/li>\n<li>Made in Bangladesh<\/li>\n<\/ul>\n","protected":false},"featured_media":29764,"template":"","meta":[],"product_brand":[],"product_cat":[2976],"product_tag":[],"class_list":{"0":"post-29720","1":"product","2":"type-product","3":"status-publish","4":"has-post-thumbnail","6":"product_cat-edu-lab-materials","8":"first","9":"instock","10":"shipping-taxable","11":"purchasable","12":"product-type-simple"},"_links":{"self":[{"href":"https:\/\/srmtradingcorporation.com\/index.php?rest_route=\/wp\/v2\/product\/29720","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/srmtradingcorporation.com\/index.php?rest_route=\/wp\/v2\/product"}],"about":[{"href":"https:\/\/srmtradingcorporation.com\/index.php?rest_route=\/wp\/v2\/types\/product"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/srmtradingcorporation.com\/index.php?rest_route=\/wp\/v2\/media\/29764"}],"wp:attachment":[{"href":"https:\/\/srmtradingcorporation.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=29720"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/srmtradingcorporation.com\/index.php?rest_route=%2Fwp%2Fv2%2Fproduct_brand&post=29720"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/srmtradingcorporation.com\/index.php?rest_route=%2Fwp%2Fv2%2Fproduct_cat&post=29720"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/srmtradingcorporation.com\/index.php?rest_route=%2Fwp%2Fv2%2Fproduct_tag&post=29720"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}